I'm not going to attempt to answer that question because there are many different answers. No one really has come up with a strict definition of Fascism, although it was theoretically described by Mussolini, Franco and Hitler in writings in the early years of the 20th century. Their versions, by the way, were all different, although all called themselves fascist. Marx defined Communism, using the theoretical work of earlier Socialists and Anarchists, but no country has ever met his definition, either. And of course, there is no definition of Capitalism at all, other than economy in which the government is not involved. Yeah, right. Show me one, anywhere, anytime. I'm not saying these words are useless, or even misleading, just that they are not exact.

Communism is generally considered the form of Socialism implemented by Lenin in the USSR, and later "perfected" by Stalin. But long after Stalin died Communism remained, and evolved, and sprang up in other places, like China and Cuba. But there were enormous differences in those versions too.

"Communism" and "Fascism", are like "Americanism" or "Freedom" or "Democracy". You can't just look them up and get an exact definition, and even in those places where there is general agreement on a vague similarity (like Canadian and American democracy or French and British capitalism) the details of each are quite different.

As a rule of thumb, a good working definition is that in Communism there is no private ownership of the means of production, it is owned by the state. (Although according to some Socialists, there is no State, the means of production are owned by the People, factories etc are owned by their workers, sort of like the way co-ops are run in Capitalist countries.)

In Fascism, the means of production is still privately owned, but economic goals and priorities are set by the state. I see Fascism as a form of Communism run by the businessmen, and Communism as a form of Capitalism run by the State.

Of course, in practice, what you actually wind up with in the real world is a hybrid system that has evolved over time through law, struggle, violence, compromise, and politics, custom and history. Even so-called Capitalist economies are not really fully capitalist, they just have different mixes. Some forms of government and economics are better than others, just ask the people who live there! But there is no pure example of any form of government or economics anywhere, just like there is no perfect marriage, or a perfect chess club.

You can't look something up in a book and say "this is Communist, or Fascist, or Socialist", or anything else, because the books don't agree and the real-world examples are all different. Political economics is more like pornography, it may be hard to define, but you'll know it when you see it. This doesn't mean you can't describe something you like or dislike by giving it a name, we all have fairly good ideas what we mean by these terms. What we can't do is whip out a book and say "this can (or can't) be fascism because it says here on page 129...".

And one more thing. Words like this don't have exact definitions. You can't figure out what "love" or "liberty" or "art" or "work" or "faith" are either by looking them up in a dictionary. Try it. It just doesn't work. Giving exact definitions to slippery, complex concepts like this is just another way politicians lie to you and get you to do what they want. Do not let them get away with it.