Answer:
China and Japan were, are and will be the most culturally and economically important nations in the Far East. They are nations that in turn have historically influenced each other, both in collaborative and mostly competitive issues. For centuries, China was a poor nation used by Japan as a "backyard", until in the 20th century China began to compete equally with Japan for the dominance of Asia.
Japan is still a monarchy ruled by an emperor. In the past, it was an expansionist and authoritarian empire, where the emperor alone had the absolute political dominance of the nation. China, on the other hand, today is a communist dictatorship, but in the past it passed through many decentralized political systems, where different dynasties tried to control the entire territory but did not achieve it entirely by the resistance of many warlords, with similar power to that of the feudalism in Europe.
Another difference between the two was that, because of its continentality, China was always much more dominated than Japan, which was never controlled by a European power. China, on the other hand, had Portuguese, English, French, and Spanish incursions into its territory.