From an episode of My Next Guest with David Letterman:
Letterman: First of all, let’s define terms. Comedian and comic: used interchangeably but mean two different things.
Seinfeld: Kind of different, yeah. A comedian is a, to me, a full-fledged, not only a monologist, but someone who can really work a room, work a crowd and has a real act. A comic… that, I think, is a notch down. Wouldn’t you agree?
Letterman: Well, you’re assigning value to them.
Letterman: I thought they were two different pursuits. That a comedian was somebody who would be funny on stage, in a theatrical production, or in film, something like that, whereas a comic would be more like what you’ve made a career of.
Seinfeld: Oh, no, no, no. You’re talking about a comedic actor. Jackie Gleason was not a comic. He started out as a comic but he was a great comedic actor. Ten Danson is a great comedic actor, but he’s not a comedian. He has no act to do in Vegas. Which is the objective.
Letterman: So you’re saying that a comedian… but I don’t understand why there is a judgment assigned to being a comic.
Seinfeld: Just because we like judging others, that’s the reason.