TIL that Fascism and Communism are not only different, but opposite ideologies. What are the main aspects of each, and what makes them so extreme and different?

by ASexyBalrog
lcnielsen

This answer by u/kieslowskifan addresses some of this question (when you say "Communism", I assume you mean the Socialist governing ideology of the USSR, rather than Marxist utopianism). And this one by u/Klesk_vs_Xaero looks at Italian fascism.