Answer: one was communist and the other, democratic. Kim ilsung from the north asked usa for help during the jap occupation. however, they did not help. when he asked russia for help, they did and thats why he started to have a thing for communism. since the idea of communism is good(not saying it works), it gained popularity in the north. in the south, a man named rhee syngman studied abroad in america and witnessed democracy. That's why when he came back to korea, he popularised it in the south. Kim ilsung wanted everyone on his side so he invaded the south in 1950.
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