The creed of fascism and communism are very nearly the same. That should give you a clue that they are related.
Communism - From all, according to their ability. To all, according to their need.
Fascism - From all, to the state. From the state, to all.
The proclaimed end of fascism is all citizens living in an ethnically or culturally homogenous state under a totalitarian government that controls all aspects of their lives. These citizens could still live as they always had so long as they were part of the ethnic and/or cultural majority.
Fascism was developed after WWI. The socialists had hoped that after decades of communist and socialist agitation, that when the Great Powers decided to go to war the workers would unite, revolt and refuse to fight.
However, the workers did not unite. Instead they all became rabid patriots for their respective nations. Fascism was a way to unite socialism with ethnic and national affinities.
Nazism was a one-off. For some weird reason they thought they could conquer the world with a German-oriented ideology. There was nothing in it for the Slavs, Jews, or other Eastern Europeans. Franco's Spain made more sense as a fascist state as they remained in Spain with no global ambitions.
Communism is tied to a universal, materialistic, amoral idea of humans as cogs in a nihilistic world. Fascism is tied to a "blood and soil" respect for the ethnic/cultural basis of the society in which it is planted. However, they disrespect the individual by imposing their demands in a totalitarian fashion. Italy failed, in part, because Mussolini was trying to tie Italy to its Roman past rather than taking account of its Catholic nature.
This distinction holds today as most neo-Marxists are internationalists while most neo-Fascists are nationalists.