Generally speaking, one of the major differences between the two has to do with clarity of exposition. Philosophers usually state their thesis up front, clearly state the premises and reasons supporting that thesis, and try to go out of their way to be clear. Theorists often don’t; indeed, they seem to aim to be unclear. You can get 20 pages into a 30-page theory paper and not yet know what the paper is trying to do.
In particular, theorists often make a move I like to call “the argument in the pocket”. What I mean by this is that instead of stating their argument, they sort of hint or gesture toward the idea that they have an argument hidden in their jacket pockets, but haven’t quite shown it to you. They’ll say things that are the equivalent of, “You know, like Arendt said,” and then you, the reader or listener, are supposed to fill in the blanks.
Let me add more here. A real problem with political theory is that this form of writing often combines ethnical claims with claims about history of thought. Political theorists like to do both at the same time. It’s a weird and subtle sort of appeal to authority. Instead of saying “it is true because