This is a fact that seems to have been largely ignored by most of the relevant historians. There were some spurts of State killing, most notably the purge of 1934. But, even that was discriminate: The disorderly segment of the party, bent on expanding the revolution for its own sake, was no longer needed and had become an impediment to the further goals of regime building.
Truncador said:
It's undeniably true that the use of State violence by Hitler in the interior of Germany was far less indiscriminate than most of the other great dictators of the age of socialism. The campaign of extermination against Jews and other putative racial health hazards was precisely targeted on the basis of formal criteria
This points to a fundamental difference between the types of socialism expressed in the age of dictators.
National Socialism's vision was to build an improved community based on foundations anchored in centuries of Germanic paternalism (this in itself founded on pastoral thinking with even deeper historical roots: see Foucault's Omnes et Singulatum). Thus the rise in power of the medical police, who became the executioners of the unhealthy; this, coupled with the popular eugenics movement of the times, and the traditional European racism, doomed particular elements of the population. The continuation of this pattern by necessity prevented the random and irrational mass killings of citizens. It was the goal of the social to lead the people to virtue and the employment of modern means was readily successful.
Marxist communism was a completely different beast. It was concerned with the obliteration of society, to replace it with some utopian unknown. Marx was familiar with the Germanic paternalism but he did not see in it the socialism: What he learned from it was the structure of absolutist powers. This expression of raw power in the pursuit of an undefined socialism resulted in the mass killings in the Soviet - since socialism was never wrong, there was never a shortage of enemies, real or imagined, and the killings were done in a wholly irrational manner, i.e., the extermination in Ukraine which lead to future food shortages and more needless death.
One might wonder about Maoism. It broke from the Soviet mold and killed far less, perhaps 30 million vs. 60 million, out of a much larger population. This hints at a common factor: paternalist thinking is a component of the traditional oriental despotism.