White supremacists, these days, just hurt people's feelings. Back when they were exclusively Democrats they were much more dangerous.
But communism, fascism, nazism and socialism is the enslavement of everyone except for the oligarchs who control every one. It is much worse than the slavery practiced in America because the people under those regimes are entirely expendable. Human life of the masses is meaningless and has no value. If the central planners deemed you as unnecessary they killed you.
In American slavery slaves had value. Only the rich could afford them and they weren't about to just kill them off as if it meant nothing. They spent a lot of money on them and they needed them to work the farms.
I would say say that socialism and all of it's variants are much, much, much worse than the worst of white supremacy in America.
I support neither. I abhor both socialism and slavery. I do not think any race is better or worse than any other race.
If you actually studied Mussolini's fascism you would understand what I mean. Unfortunately the left has contorted fascism to mean a whole lot of things it never meant. I've even talked to people who think fascism is just another word for racism. This is NOT what Mussolini thought. In fact as long as you were born in Italy he didn't care what race you were.
Hitler was the one who was obsessed with race but then so was Karl Marx. Hitler was not a fascist, he was a national socialist.
Fascism is clearly just another variation of socialism. If gave a little more leeway to businesses in that it allowed business owners to keep running their companies but only under complete control of the government. Socialists, communists threw the business owners out and put in their "experts" who always just screwed everything up.
This notion that socialism and communism are on the extreme left and fascism and nazism are on the extreme right is just absurd. It was propaganda that was put out by the American Progressives after WWII broke out. They stopped their love affair with Hitler and Mussolini because they didn't want to be seen as un-American. So they shoved the Nazis and fascists over to the right and started a media and education campaign to spread that fallacy.
There is no room at all for individual liberty if you try to squeeze between those authoritarian regimes. The more logical scale is total government control on the left and anarchy (no government at all) on the extreme right.