Different Paranoias

Hitler and the National Socialists were paranoid about the Jews, about Slavs and Communists, and just plain hated other groups without necessarily feeling any paranoia about them: Roma, homosexuals, the disabled.

Stalin and the Communists were paranoid about kulaks in particular, or anyone who had a little something: power, money, connections. The obvious flaw in that was that as they gained power, money, and connections themselves they increasingly became paranoid about each other. 

So both were paranoid but the targets were qualitatively different. Being a kulak was a role or position you had in society.  Being a Jew was something that you were, and ultimately ineradicable. I oversimplify greatly, for both groups had a dozen other hatreds they might kill you for and were indistinguishable in that way. 

Yet I wonder if that is part of why we remember them differently.  Stalin killed more Jews but Hitler remains their iconic enemy. The other explanations don't go away. Many Jews had left for the West between the wars - kulaks and tsarists did not. News of Stalin and the Soviets was buried deeper in the east and did not penetrate the discussions.  Being Jewish was more of a group identity than being a kulak, so when a Jew told her story she was aware of others she was writing for and they of her, creating a mutual library of their experience. Leftists in the west continued to admire the USSR, while no one admired Nazi Germany after WWII, however much they might have before.  The leftists were something of a fifth column in that way. All that is true and perhaps is the entire explanation for why Hitler has the name though Stalin was objectively worse.  But I would like to add the possibility that it was a difference in the type of paranoia at the core of each ideology that causes us to see them differently.