What political tensions, suspicions, and conflict of ideologies led to the Cold War?

Okay, so the government philosophies of the United States and the Soviet Union could not have been more different. The United States was a democracy which means that its citizens have freedom of speech and have many liberties. The Soviet Union on the other hand was Communist which means that citizens have no rights and the federal government controlled everything. This difference led to a conflict between the two nations on how to rebuild Germany and Berlin after WWll and spearheaded events such as the Berlin Airlift and the building of the Berlin Wall. Back in the United States, Communist was a big no-no and suspicion ran high, especially after Wisconsin Senator Joseph McCarthy claimed he had a list of over 200 government officials who have Communist sympathies. This event was the first time Americans started to have a distrust in the government and later would lead to troubles in the 1960's.