Ideology:
The ideological differences between the two blocks go back to the Bolshevik Revolution in 1917 in Russia where communists succeed. A capitalist economy is based on private ownership, private profit and free competition. A communist economy is controlled by the Government. These ideological differences lead to tensions. In early stages already the USSR tried to spread communism, which the USA tried to prevent. For this reason it did not recognise the USSR until 1933. These differences where covered during the war against the common enemy Nazi-Germany.
Marshall Plan:
After the World War II the struggle started again and heated propaganda started. To prevent communism from spreading George C. Marshall developed the Marshall Plan in 1947. It was the USA's initiative to rebuild Europe by giving the countries economical support in order to stop communism from spreading. Many European countries accepted the money and allowed the Marshal Plan to succeed. In turn the USSR prevented Poland and Czechoslovakia from accepting the money.
Arms race:
The situation heated up further and both sides produced nuclear weapons, which caused an arms race. This race was used by both sides to demonstrate the aggressiveness of the other side, which turned into a propaganda war. For example on both sides videos where produced and broadcasted in order to produce fear and support against the other side.
The Cold War had its roots in ideological differences between communism and