Immediate conflicts: ... The USA had atomic weapons and the USSR did not. (The US would not share that technology with the Soviets.) ... The USSR did not assure that free and fair elections took place in Eastern Europe -- it saw to it that Soviet-aligned governments were installed there. ... Tensions over the East Germany / West Germany and East Berlin / West Berlin division of territory.
Deeper causes: The USA was committed to capitalism and democratic institutions of government. The USSR was committed to communism and imposed authoritarian government. The Cold War was mostly a tension between these worldviews.
The reason why members of the year born middle class and Brazil protests the coffee Elite in the 1920 was because governments was controlled by the Elite landowners who grew coffee. The first presidents were elected by rich landowners that grew coffee and this is why the first Brazilian presidents were called coffee president
