In historic China, Korea, and Japan, empires not far from each other, they each struggled and flourished, grew and fell, and advanced through time, misfortune, and prosperity.  They were all similar, thriving on the same values, sharing the same stances on outside trade, and even sharing similar characters in their written languages, yet they remained completely different.  They shared similar views in politics, the place of women in society, military power, and rulers who were strikingly similar.  Somehow, they also ended up completely different in many of the same areas.  The differences in these areas define their cultures and built empires that reigned for centuries.
Politically, the structures of all three nations and empires were somewhat similar.  They all had a relatively similar administrative systems, ways of dealing with domestic affairs, and ideas on foreign relations.  Although when it came to political views they were all very similar, there were differences as well in areas such as entrance into the administration.  In China, during the Ming and Qing dynasties, there was a very strict structure to their administration.  At the head was the emperor, then his council of advisors.  The emperor stood strongly at the head, functioning as the executive branch in their political structure.  He held council with his advisors, and ultimately made the final decision using his own judgement based on what he and his advisors had discussed.  Along with the emperor and his council were the foreign rulers that were involved as a result of the tributary system, a system in which the rulers of  all other countries were regarded as “younger brothers” of the Son of Heaven, who was the emperor of China (China being recognised as superior).
Japan differed from China in more ways than one, though.  Japan did have an emperor, but he stood more as a figurehead than a functioning executive.  Instead, Japan was lead by the shogun, a military leader who made the final decisions after consulting with the emperor and the bakufu (a council of “daimyo”, which were similar to feudal lords, and elders, who were considered to be wise and knowledgeable).  Japan also had an aristocratic class, as it was a bureaucracy, called the daimyo, who stood as war lords as well as landholders under the shogun, and were directly subordinate to the shogun.
Like China, Korea did much the same.  In the begining, Korea aimed to be similar to China in every way they could, and that included their administrative structure.  The country did have a functioning emperor, much like China and joined into the tributary system soon after their founding.  Unlike China, who had no aristocratic class, Korea was similar to the bureaucratic setup of Japan, having an aristocratic class that was referred to as yangban (meaning “two groups,” the civilian and the military, the military being the aristocratic class).
China used its military as a way to control their domestic affairs.  The military, called the banners (bannermen) in the Qing dynasty, was used to protect and expand the nation’s boundaries, people, and internal peace.  While the main focus of the nation’s economy was on rice plantations and agricultural activities, military control seemed necessary to controlling the peace between peasant farmers and central China.
Like China, Japan also controlled its domestic endeavors by way of military control.  The shogun himself, held at the head of the government, was a military leader.  Beside the shogun stood the daimyo, the smaller war lords who pledged loyalty to the shogun.  Under the daimyo stood the samurai retainers who were a warrior class, hired to protect and serve the daimyo and his han (the fief or land that was upheld by the daimyo).  Although there were peasants and farmers who were beneath those ranks, the society was largely under the control of the military and, in turn, the domestic affairs of the Japanese were controlled by the military.
Korea was no different, as it attempted to be as similar to China’s structure as possible.  The military played a large role in the control of Korean domestic affairs.  Korea, like China, was largely dependent on their agricultural activities, but the military was used to prevent revolts and maintain the peace between the peasant class and the central government.
In China, the entrance into administrative posts was extremely difficult.  In order to become an advisor or larger part of Chinese society, one had to be male, well educated, and of good status.  Peasants and uneducated sons had little chance of ever moving up the ranks and were often held back by their responsibility to their family and the family farm (as most, if not all, families were agriculturally involved).  Candidates for administrative positions had to be literate, well versed in Confucian classics, and involved in the military in some way.
Korea was extremely similar.  Peasants and uneducated sons were rarely allowed to leave their class or family estate, and the administration was a class of the elite, hand chosen by the emperor himself.  Because of this reason, it was extremely hard, if not impossible, to enter the administration from a lower social class.
Japan was similar, yet it was easier to move up in the ranks than in the other two countries.  All militarily involved men could move up into the administration, and wise elders were often chosen to enter the bakufu.  A good example of this would be Toyotomi Hideyoshi, one of the three largest political figures that led to the Tokugawa era.  Hideyoshi was the son of a farmer who became a samurai.  He had no family name to honor as he moved up in the ranks and eventually decided to adopt the name of Toyotomi, meaning “abundant provider” in order to embellish his reputation for improving the material standards of his domain.  He eventually rose to the position of military leader.  Unlike in China or Korea, the Japanese system allowed a peasant to rise through the ranks and eventually become an administrator/leader.
When it came to foreign relations, China, Japan, and Korea all had similar opinions.  China allowed foreign relations with the west (Europeans) in the early Qing dynasty (although the foreigners were restricted in where they could go), but eventually expelled them.  When the Europeans came, they offered several trading options (clocks, spectacles, manufactured goods, etc.), but they also offered Christian ideas.  Along with the goods that traveled with the traders, missionaries also came to reside in China.  The Jesuits (Portuguese missionaries in the religious order of the Society of Jesus) spread Christianity to China and other eastern nations, but soon wore out their welcome and were expelled.  Soon after, China ended all relations with the western cultures, including trade (although Chinese officials and Emperor Kangxi attempted to keep trade active for a short while after that).  China did have relations with Russia for a while, although it was a strained relationship as Russians refused to be subordinate to the Chinese and refused Chinese customs.  That relationship was a lasting one, but it was far from ideal for either party.  China did remain neutral and did trade among its close neighbors such as Japan and Korea, although it was extremely limited.
Korea, a nation that almost mirrored China, never opened relations with western cultures.  For this reason, Korea was referred to as the “hermit kingdom”.  Korea, although not welcoming to westerners, did trade amongst close neighbors and welcomed interactions between it and China.
Japan was relatively closed to western ideas as well.  Although in the beginning they welcomed westerners in the, the relationship was not strong and eventually, they closed off from relations with the west.  The first westerners arrived on a Chinese ship after being blown off course by a typhoon.  With them, they brought tradable goods and Christian ideas, much like what occurred in China.  For a time, the Europeans remained peacefully in designated areas, and spread Christianity (mainly the Jesuits, although the Spanish also sent missionaries).  Europeans were tolerated for a time, although Japanese people were forbidden to leave Japan.  But, such peace between the Japanese and Europeans was short lived.  As Christianity grew, missionaries and followers became more bold, destroying or repurposing sacred shrines for Christian schools and churches.  Such activities were not looked upon kindly, and missionaries were expelled (not before several missionaries and Japanese converts were put to death).  Trade remained open for a time, even while the Japanese suppressed the western religion, but eventually the trade relations were ended.  Although most trade relations were ended, the Dutch, who did not allow religious matters to effect their trading, were allowed to remain for a short period each year on the island of Deshima in Nagasaki harbor.  Conditions were not the best on the island, but it was the last remaining opening to the west.  Relations with Japan’s close neighbors were minimal but not nonexistent, but Japan was largely isolated by its own choice.
Socially, these three empires were also similar in several ways.  All of them shared similar ideas about the position of women in society, the ability to move from one social class to another, and their ideas on education.  Although there are several similarities, there are also several defining differences such as their religious views, class structures, literature, and arts.
In China, the class structure was very simple.  There were the administrators and the military men, and then there were the peasants.  Within these classes there were few differences other than the slight variation of influence and wealth, but the two classes were very different.  Administrators and military men held a lot more power than peasants, some more so than other, and often were either influential in politics or wealthy, sometimes those two factors played off of eachother.  Within the peasant class, most were farmers that were granted land to work.  They were usually impoverished, although some peasant families were more wealthy than others.
Korea was similar, although there was an aristocratic class as well as a civilian class, unlike China who had no aristocratic class.  This social ladder was called yangban (“two groups”), although there was a class unrecognized in the name.  Above the civilians were the military men and families who played the part of the aristocrats.  Then there were civilians, who were average people with an average amount of money, land, and power.  And finally, there were the chonmin, who functioned as slaves and labored on government plantations or did designated jobs such as butcher or entertainer.
Japan had a somewhat more complex social ladder with four primary social classes.  There was a very big line drawn between each of these four main social classes, and intermarriage was, in theory, forbidden (although it was ignored in practice).  At the top of the social ladder were the warriors, not surprising as Japan was built on and functioned through the military.  Underneath the warriors were the artisans, given their position because they produced fine works that helped them produce wages.  Just below the artisans were the peasants as they too produced something to earn their share.  And at the bottom of the social ladder were the merchants, given their position because they themselves did not produce what they sold, and instead lived off of the wages they got by selling other's’ work.  Although there were four main social classes, there was a fifth class, referred to as eta.  The eta were a class of outcasts in Japanese society, largely discriminated against by those with higher status through laws and restrictions (where they were allowed to live, what they were allowed to wear, eat, and even what hairstyles they were permitted to wear).
Social mobility was nearly impossible in both China and Korea.  It took a great amount of effort and influence to be able to climb through the ranks, and few succeeded in doing so.  With peasants so poor and administrators being so influential, it was rare for an individual or family to change their social status.  Inheriting the family trade, whether it be an administrative position or farmer, was something that was very common.
Japan was less rigid and there was room for social mobility.  As before mentioned, Toyotomi Hideyoshi made a huge jump in society.  Through the use of a military position, peasants could become military aristocrats, and with them, their family rose through the ranks as well.  Although there were ways to do such things, the eta class were not allowed to escape their social ranks, and the position was inherited from generation to generation.
Religion was a topic once again shared between China and Korea.  Although China did experience a time of Christian infiltration, the nation was purged of the religion and became largely based Confucian concepts (although there was a time where Buddhism was influential).  Korea followed Confucian concepts as well, attempting to follow in their powerful neighbor’s footsteps.
Japan was different though.  Called the land of the gods, Japanese people worshiped several gods (referred to as “kamis”) who ruled over certain concepts (water, luck, relationships, wisdom, etc.).  Japan too experienced a time of Christian conversion, but the period did not last long.  Buddhism also resided in Japan as a popular religion, and several monasteries were founded on the islands.
The arts flourished under these empires, and the works created and published during their times still are held in high regard.  Revolutionary novels, poetry, architecture, art, and entertainment.  Each empire had their own unique style, and that is what defined them, although they were all new advances at the time.
Women in all of these nations were considered inferior to men in several ways, most notably in China and Korea.  In China and Korea, women were used as slaves, working the fields, being used as bargaining chips in arranged marriages, and being used for reproduction.  Women were inferior to men in every way.  They were not educated (except for the very fortunate) and were kept on tight leashes.  Female children were often killed as they were not as prized as males, and those who were kept often led miserable lives, and could expect to be treated as slaves, easily killed and disposed of.
In Japan, women became more inferior than they previously had been, especially in the samurai class.  Women who previously enjoyed a life that was close to what males experience (not as freely, but a similar version where both genders were educated and both male and female samurai were trained in the art of war) were forced to live much more isolated lives.  They lost their privileges to be educated (except for a very privileged few) and were forced to be more submissive to their husbands.  They were used more as trophies and representations of their families and husbands than the warriors and workers of previous times.
Education in all three of these empires was similar.  All of them offered education to those who were wealthy or privileged enough to obtain it (meaning they were either wealthy enough to have a school within their immediate family, or they were offered an education by a wealthy relative).  In the schools, these select students would learn to read and write, and studied Confucian classics and concepts, which were viewed with high regards as society revolved around such concepts.
In China, architecture, pottery, and literature were the most notable advances.  When it came to architecture, the imperial city (“Forbidden City”) was a beautiful, revolutionary advancement.  With elegant decorations, expensive furnishings, and large rooms, the city was an extraordinary thing of beauty, that of which was never before seen.  Pottery was popular as well, porcelain being a popular medium among potters.  Among the most notable pieces were the blue-and-white porcelain objects of the Ming dynasty that are still coveted today.  Finally, in literature, fantastic new novels were being written.  Some of the most notable were about social issues and errotic scenes that held moral lessons.
In Japan, literature, theater and art works were the most notable developments.  In literature, poems and novels expressing intense emotions were the most notable advances.  Some of the biggest names were Basho (a writer of poetry) and Saikaku (a writer of novels considered to be the finest in Japanese history; most notably the writer of Five Women Who Loved Love).  In theater, a new form appeared called Kabuki, which involved violent, dramatic themes with intense music and was originally performed by prostitutes.  Finally, the most notable development in artistic works would be the creation of woodblock prints depicting the daily lives of the working class (the most notable works being Thirty-Six Views of Mount Fuji created by Hokusai, Fifty-Three Stations of the Tokaido Road by Hiroshige, and the artist Utamaro who depicted errotic and sardonic women doing everyday activities).
Similarities and differences litter these empires’ cultures, values, and traits, making them strikingly similar and different at the same time.  Although they had very similar methods of domestic control, relationships with foreign nations, and ideas on education and the position of women, they have striking differences in other areas.  The structure of their administrations and social classes, their religions, their arts, and their social mobility are all enough to clearly define them as individual countries with very different cultures and traits.

Resources
Japan: Its History and Culture written by W. Scott Morton and J. Kenneth Olenik
Compiled Primary Source Reading from various sources
World History (textbook) compiled and written by William J. Duiker and Jackson J. Spielvogel (the Pennsylvania State University)