They strike me historically as quite similar countries. Same fertility rates today. Same machine gun droning on the television (though Japan’s is underpowered). But with this exception. Spain was made near famine free by the hand of nature (the Columbus expedition could only have been financed by a rich country). Japan was made near famine free (largest city in the world in 1800) by the hand of man, through various ingenious methods. Thus Japan made unusual progress c. 1900, while Spain was described as unusually stagnant by northwestern European standards (though it was far richer than Japan). Today, the countries are basically similarly rich, but Japan has the six points higher average IQ. Homicide rates low in both.
North China was very different, and adapted its language and culture to fit its higher famine frequency. Thailand had regular catastrophic flooding. The General Secretary speaks very slowly when addressing the public, to make sure every word is heard and no calorie is wasted. Mandarin doesn't have many voiced sounds, either.
There are parts of China that are like Japan.