Comment: No it is not. But there is no rational way of measuring it. Nor is there any sensible reason to do so because 'not as evil as X' is a seriously meaningless claim. 
So we might as well treat it as if it's equal. 
That said if there is a difference it's not in what was achieved by the evil person. It's in what beliefs guided his evil. 
So I have no qualms putting white supremacists all in the same 'worst of the worst' rating. The only difference between any of them and Hitler is opportunity.