These terms tend to get conflated, especially in parts of the web where people use their real names.

Yeah. Total OpSec failure, as I see it. I learned that hard on Usenet.

Harassment is arguably a kind of trolling. And trolling is arguably a kind of harassment. But then there's the ideal of free speech.

I always seen it like this: trolling: silly arguments, maybe attacking a person in a thread about their viewpoint (ad hominem) during a thread. While harassment is insulting a person, everywhere regardless of the thread going on, as well as attacks while the person is not participating in a/the discussion.

Yeah, I get that. But what happens is that threads on one site become trolling topics on other sites. So harassment becomes part of the trolling game.