What were the reasons the United States and Soviet Union could not agree on a workable postwar relationship?

The U. S., being capitalist and democratic, and the U. S. S. R., being communist and totalitarian, could not work out a workable postwar relationship for a variety of different reasons, including the relationship between President Harry S. Truman and Josef Stalin, opposing ideas in relation to the treatment of Germany after the war, and the U. S. wanting to contain communism while Stalin and the U. S. S. R. wanted to expand their territory into Eastern Europe.