How did Stalin and Trotsky differ in their politics?

Stalin and Trotsky had different views on many issues regarding Marxism - Leninism. The most significant difference was that Trotsky can be said to have been a true Marxist, while Stalin took a more "practical" view on how Marxism should be applied to the Soviet Union. Another key difference was that Trotsky believed that debate and different points of view on various issues were healthy for the communist party. On the other hand, Stalin believed that decisions, once made, were not open for discussion.