Fascists believe in a strong hierarchy that makes sure the collective will prevails (dictatorship). Communism is about ending all forms of hierarchy.

The difference to socialism is a bit more nuanced. But I would say most of today's "Communists" are actually fascists.

Mussolini was right, both the 20th and 21st century are the centuries of the collective. Hayek even wrote about this in his "Road to Serfdom"