I fail to see how we should differentiate between "main" and "primary", considering the fact that both "main antagonist" and "primary antagonist" are the same things.

@Valkerone

Primary Villains only exist in a long running franchise or a series with multiple main villains, unless there's none of them taking an overarching role that overshadowed the rest of main villains. In my opinion, this is BEYOND main antagonist and should be labeled independently.

Anyway, this is only my personal opinion and I understand there would be difference.