An interesting anecdote from the thirties.  I found this particularly interesting:
Political ignorance also may have hurt Heinlein’s campaign in two other ways. First, Heinlein believed that he was harmed by the fact that the Communist Party had endorsed him. Although a leftist himself at the time, Heinlein was very hostile to the communists in the 1930s, denouncing them as “red fascists” no better than the “brown fascists” of the far right.
As with Heinlein, it was clear to most at the time that fascism and communism were just two slightly different flavors of the same totalitarian political phenomenon, and much of the American left admired both.  It’s only the modern left that has developed an amnesia about it (somewhat deliberately, by rewriting history in academia), declaring after the fact that they are political opposites on the simple-minded one-dimensional left-right spectrum.
I will say one thing that was worse, or at least different, about Nazism, though.  This morning I heard someone from Libya saying that if reports coming out of there were accurate, that a “genocide” was going on.
No.  That word has become devalued in recent decades (partly to minimize what happened to the Gypsies and Jews during the war, and as a way of reducing support for Israel).  Killing lots of people is not genocide.  Even ethnic cleansing in a region is not genocide.  Genocide is the deliberate attempt to wipe out an entire “race” of people (while race is largely a social construct, in this case use it as shorthand for “group of people sharing a large genetic heritage”).  Hitler was, I think, unique in his desire to do this.  Well, except for modern Islamists.