Churchill claimed that the Soviet Union did not want a war, but to get the fruits of war and indefinite amount of expansion. It is important to note that after World War II, no country was foolish to go for another war. Basically Churchill also wanted balance of power, as has been mentioned in his speech.
Hitler believed in the Aryan race. He believed they were stronger, more successful, and just better in general. He wanted to rid the world of people who were not of this race, in order to create a "better" world.