I think George Steiner had a point when he said in one essay that Hitler's idea of murdering every last Jewish child that existed on earth was particularly reprehensible and somehow even worse (if anything could be worse) than what happened in the Soviet Union under Lenin and Stalin. But he should have included the Roma (Gypsies) in this ultimate condemnation of the Nazi regime. That's the thing, whenever anyone's arguing a particular side on this issue, they always leave at least one crucial part out of it.
The fact of the matter is, Nazi genocide was directed not only against Jews but also against the Gypsies. Gypsy children and even infants went to the gas chambers. And the next target on the list? Slavs. In fact, as far as I recall, Russian POWs were the first (experimental) victims of the poisonous gas Zyklon B at Auschwitz. In other words, Slavs were only one step above Jews and Gypsies on the Nazi racial ladder. They, too, were ultimately expendable.
I think the normal human mind has difficulty grasping the full range of human evil. Which is to say, that the Soviet democide (which is to say, deliberate and/or negligent governmental actions resulting in the mass deaths of certain civilian populations, usually on the basis of class or nationality or political allegiance) was, to my mind, somewhat different than the Nazi genocide, although both were similar in their results - millions of deaths of innocent people. In the end, it hardly matters who was responsible for more deaths in the cursed twentieth century - Stalin, Hitler, or, for that matter, Mao. They were all mass murderers and they all have blood on their hands. I hope they are all rotting in hell, and indeed, I wish Dante had invented a special circle of Hell for criminals of this kind.