The alliance set up during WWII soon collapsed

The alliance set up during WWII soon collapsed
Relations between the Soviet Union and the United States were driven by ideological, political, and economic factors, which led to changes in their cooperation and often bitter their superpower rivalry after the second world war. The distinct differences in the political systems of the two countries often prevented them from reaching a mutual understanding on key policy issues and even, as in the case of the Cuban missile crisis, brought them to the brink of war. This rivalry was nothing new between the two countries, their ideological conflict started since the Bolshevik revolution in 1917. The USA tried really hard to stop the revolution and the communist rising to power in Russia during their civil war in which they supported the "Whites". After the civil war hostility among the two countries kept increasing for instance, the League of Nations didn't recognized the USSR until the 1930s. This impartiality continued during the year, escalating dreadful clash.
Capitalism and communism are different in their political and economic ideologies. The most clear difference is there industry. In the communism world industry is own by the state. On the other hand, in a capitalistic world industry can have private owners. While the profit of any enterprise is equally shared by all the people in communism, the profit in a capitalist structure belong to the private owner only. Whereas the private party controls the resources in capitalism, it is the society that controls the whole means of production in communism. Another difference is that for Communists, the society is above individuals. But for capitalists, individual freedom is above everything, the state or the society. The capitalist system is an self regulated economy, whereas communism is an economy run by the state. Also in capitalism, the individual has full control over production and decides on the prices. Contrary to this, it is the society or the government that determines the prices in communism.
The USA and the USSR thought that its particular political philosophy was the best one for the world, that their system was the most fair and best creating a just society. How they put their opposing ideologies into work wasn't so different from each other. Each side believed that it offered the true path to peace, justice and plenty for all. However they were as well motivated my self-interest. On the one hand, the USA, wanted to established markets and open doors to free trade. Beside this way they could protect their economy from another economic crisis like the one on 1929. Also President Truman and most of the post-war US administration belief that what's good for America is good for the world, which wasn't always true. On the other hand, the USSR, wanted to secure their borders, recover their economy from WWII and to regain strength as motherland of communism. Also Stalin thought that what's good for the USSR was good the workers of the world, which also wasn't always true.
It's difficult to separate actions based on ideology from those on self interest. However, I think what motivated both the USSR and the USA is the search of power, and controlling the world to shape it as they feel it would be more convenient for them, in other words its simply old fashion imperialism.