What is the difference between the United States and Japan?

I came across this idea after comparing the differences between the United States and China.
What is the nature and concept of the world of America?

Koreans like me often recognize the United States as a nation, people, and Christian world. However, in reality, Americans had too many races, ethnicities, cultures, religions, and ideas. The United States that I experienced seemed to be a combined federal system of various countries. The concept of the federal and state governments was also difficult to understand.
In conclusion, it seems that the centralized system and the decentralized system are combined.

Korea is a centralized system, so it is difficult for me to understand the American state system. So, once I looked at the big cities of the United States, I studied about the American state system. In my view, the United States was completed as the pioneers from Europe expanded from east to west. Korea and China are different from the history of large cities built as pioneers descend from North to South.

Looking at the map, the United States and Japan are large cities created from east to west, while China is created from north to south. Japan achieved national unification in the early 17th century, and Tokyo was completed as the capital. Japan had a much later national unification and centralization than Korea and China.

Tokyo became a capital city of Japan a little earlier than the time of American independence. After all, the United States and Japan were born in a similar era. However, the birth and completion process of Japan's people and nations is similar to that of Korea and China. In conclusion, if Korea and China had completed the people and the nation for 2000 years, Japan is different from completed it in only 500 years.

The United States and Japan are similar in the country's birth and completion, and the fact that large cities were created from east to west. However, Japan has the same process of birth, development and completion of people and nation as the countries of East Asia, Korea and China.

Japan was the latest among East Asian countries to complete centralization and national unification, so it was the fastest to accept Westernization. However, Japan aimed to build an East Asian empire ruled by the Japanese emperor, not democratic republicanism like the United States.

I think that Japan should be compared to the United States rather than China to discover the differences and similarities between East Asian and American civilizations. For Westerners, Japan's 500-year history will be easier to study than China's 2000-year history.