I think communism is fundamentally incoherent and always evolves into fascism. Communism is a reaction to problems that it cannot solve by the methods described by the theoreticians, but since those theoreticians are always opposed to fascism the fact that communist states always evolve into fascism is deeply uncomfortable for the hard left, so they try desperately to create a distinction where there is no difference.

Authoritarianism doesn't really cover it because you can have authoritarian monarchies, like Saudi Arabia, or theocracies like Iran. You can't call these communist or fascist because they have different corporate and political cultures.

I think communism is more adept at internationalisation than fascism because the underlying narrative is inclusive and communicable, where as with fascism they've reached a state where they don't care about convincing anyone outside the state, they just need internal coherence and compliance, because they consider themselves to be in competition with everything outside the bounds of the state, so ethnic homogeneity is more likely to succeed at that than pluralism. But ethnic homogeneity isn't the point, control and status is the point.

In the US and Europe they are trying to deploy an experimental form of fascism where you have musical chairs for different facial complexions and hair colours and genders and whatever, so you have diversity of everything that doesn't ultimately matter to the state, and absolute homogeneity in everything that does matter. Any deviation from the party like leads to excommunication or a Kafkaesque sanction, administered by the people closest to you, as they are put under pressure to disown you and anyone who expresses a thought that might be deviant.

Its not a very sustainable form of fascism though, because it has no historical ethnographic narrative to draw on, to give itself a positive sense of the future.

Say what you want about the Nazi party, they were optimistic at least. That can't be said for a fascist culture that believes:

Ethno-fascism can buy people off with promises of future gain, where as the fascist experiment the West has been running needs to buy people off with payouts today, whether corporate welfare or covid stimulus, which is how the West quickly bankrupted itself, by layering payouts on top of the liabilities it built up on behalf of the boomers.