The point being, of course, that even if one accepts the dubious principle that killing "outsiders" is more forgiveable than killing "your own", that doesn't excuse Hitler very much because he did target "his own". It's all very well to say that if you were Aryan you were all right, but this ignores the fact that the Nazis murdered or otherwise persecuted not just Slavs and Polish Jews but German Jews, and also the disabled, homosexuals, those who held what were regarded as unacceptable religious beliefs, and so on. It's all very well to say that if you were an Aryan you were all right, but that wasn't the case if you were a disabled Aryan or an Aryan who was also a Jehovah's Witness. Nazism was like all forms of fascism in that it fetishised strength - or what it regarded as strength - and sought to strengthen the nation by weeding out what it regarded as weakness. So woe betide anyone who fell into the category of "weak". In fact, of course, the duty of a government is to care for all those in its charge, especially those who need more help than others or who are marginalised in society. If you want to make it simplistic and personal, Stalin was a paranoid maniac who eliminated people he thought was a threat, but Hitler was a bully who eliminated those people with the least ability to fight back.