The seeds of the cold war were sown with the Russian revolution of 1917 when the communists took power. The USA and Britain did not want the same thing to happen in their countries. The failure of the Russian Civil War was a consolation for America.
During the Second World War alliance, the UK and America vehemently fought against Russia.
Stalin distrusted Germany; a distrust which grew further with the development of Atomic Bomb. This was further worsened with the Marshall Plan in 1947 to help rebuild Europe. The United States extended support for this.
Capitalism, the trump card of Stalin, got a boost with the formation of Council for Mutual Economic Assistance (COMECON) in 1948.
The Cold War was a persistent ideological schism between the U.S. and the U.S.S.R but lacked any physical combat. However, World War I and II cemented the conflict. KGB at one side and CIA M16 combination at the other end has made the situation scary.
For a short time, the U.S.S.R and the United States were able to put their ideological differences aside to ensure the safety of Europe. In the process, Germany was to be divided into four zones, and all the Nazi criminals were sent to trial. Russia got an entry to UN.
But the inherent difference between the roles of the individual due to the ideological difference had already laid the foundation for the schism.