Are you sure about that?
Well considering that Karl Marx is the father of modern communism and the greatest influence on socialism, Nazism and fascism then I would have to say that bigotry is inherent in all of those variations of socialism.
You see, Marx and Hitler have a whole lot more in common than political philosophy. They both were self-hating Jews who wished the exterminate the entire Jewish population from the earth. The both hated blacks. Marx thought they were inferior sub-humans and referred to them with the "n" word.
However, Hitler was more interested in German paganism while Marx wrote love poetry about Satan.
So the real question is where did you ever get the idea that socialism was any different that Nazism. Oh and by the way, Mussolini, not Hitler, is the father of fascism. Mussolini, unlike Hitler and Marx, didn't seem to care so much about race, or at least he never made any overt comments or actions against any particular race. He was not for an Italy only for Italians. His criteria just seemed to be if you were born in Italy you were an Italian. However, that said, he might have been a flaming racist in his private life.
So you want to try again? What is the difference between socialism, communism, Nazism and fascism? They all do not allow private property rights. They all look as mankind as a collective and not as a bunch of individuals. They all promise that the government will take care of every need by stealing money from the rich until there are no more rich. They all operate under the mistaken notion that the government can control the economy without collapsing it. They all incorporate the Labor Theory of Value rather than letting consumer demand set the value of a product and/or service.