Under communism everyone takes care of the needs of everyone else and the need for government fades away. Socialism is supposed to be a step on the evolution to communism. Since none on the ruthless leaders who called themselves socialists or communists or nazis or fascists ever had any intent to give up power and let government fade away then they were never the word that they called themselves. They were just variants on the theme of tyrant. I think I will call them a rose.
The best word for both is totalitarians, as both wanted to exert total control over their people.