The Marshall Plan was more economic, as it sought to give aid to all of Europe (although it was refused by Stalin for Eastern Europe). It simply wanted to promote economic reconstruction in European countries so that Europe could be back on its feet. This move showed America's desire to help out devastated nations and the rise of the US as a major world power.
The Truman Doctrine was more political. It imposed the policy of containment, which aimed to give economic and military aid to countries being threatened by Communism. It wanted to "contain" Communism so that it didn't spread. At that time, it was helping Turkey and Greece.
The Truman Doctrine was devised by President Truman to provide short term relief for Greece and Poland. With a civil war in Greece being won by the Communists, it was believed that the domino theory would occur, which was that if Greece fell to Communism, so would Turkey and eventually all of Europe. The Truman Doctrine was short term aid to prevent the nations falling to Communism and stopping the Domino theory. $400 million dollars were given to Greece and Turkey to prevent them turning Communist
The Marshall Plan was a long term plan devised by US Secretary of state George Marshall to help all the countries of Europe by combining US resources with local resources of a country. 16 Countries met together to provide a list of things needed to help rebuild the shattered economies of the European nations. $14 Billion dollars was required to put the Marshall plan ahead, and this was granted, however the USSR saw this as Dollar Imperialism and set up Comecon and Comniform in response, which failed after a few years of service as they did not have the resources to control the economies and political systems of the Satellite states to full effect.
Hope this helps :)
Truman Doctrine promised economic and military aid to countries threatened by communism that year, turkey and greece
Marshal plan: Rebuilt the economies of war-ravaged western Europe to make them less susceptible to communist appeals against capitalism
Not only did the US want to stop communism in Europe, they also wanted in stopped virtually every where. Don't forget the two "hot wars" inside the cold war, Vietnam and Korean.