The Fascist theory was of a unitary, totalizing state ruled by a leader acting as the embodiment of the will of the nation. No power centers in opposition to the embodied will can be tolerated; church, family, education, and civic institutions must all become organs of that will.
One way to tell if you’re dealing with an actual Fascist is whether your subject has that theory of state power. If he doesn’t, you might be dealing with (say) a garden variety conservative-militarist strongman like Admiral Horthy in Hungary. Rulers like that will kill you if you look like a political threat, but they’re not invested in totalitarianizing their entire society.
Source: Spotting the wild Fascist
I think the greatest essay I read on the subject was from Ayn Rand. She rightly
placed all forms of collectivist governments to the left with actual Democratic
Republics on the right. The phony left-right paradigm was invented by the
left to make Hitlerian “fascism” the devil to the Marxist good.
Her point was that any system that subordinates the individual to some greater
(often undefined) good is by nature collectivist. The old definitions of
communism socialism and fascism only differ to the degree that private
property rights are allowed to exist. While all three systems were corrupt,
private property rights existed in Nazi Germany (especially with the crony
capitalists who were almost all party members, but even then, these rights
were heavily regulated and controlled by the state.