Is Leslie Nielsen's distinction between a comedian and a comic actually insightful, or is he just telling a joke here?

Time magazine did a story about Michael J Fox appearing on the TV show Spin City. The essence of the article was that Fox understood what it meant to be a comedic actor, as opposed to the explosion of standup comedy based shows at the time whose principal actors were comedians, rather than comedic actors. Time called Fox's turn a relief and delight to watch a professional at his craft.

This is why Nielsen's line is insightful. A standup comic walks onto an otherwise empty stage and creates situations for the audience. They are punchers who initiate the action.

Comedic actors are, by contrast, counter-punchers. They are always responding to situations not of their own making. A comedian may or may not elicit empathy from the audience, but a comedic actor must do so. They are a stand-in for the audience, itself. Their reactions dropping the wedding cake or whathaveyou tap in to our own reactions, albeit in an exaggerated form. The emphasis in standup, on the other hand, is surprise. The standup reacts in ways we would not.

Nielsen was a smart cookie. He knows that, for his own schtick, it is the audience which does the heavy lifting. This was the distinction he was drawing in his quote.

Roger Ebert in a review of The Naked Gun 33 1/3:

It would be fatal to the movie if [Neilsen] ever betrayed the slightest suggestion that [he knew] funny things are going on.

He doesn't know that his double entendres are double entendres, which makes them funny. So, broadly, a comic actor is someone who can play comedic characters well, while a comedian is someone who tells jokes.

It's not a hard line between the two, though; there are stand-up comedians who create characters for their jokes, and movie characters who know they are being funny.

I'd describe a comedian as someone who tells jokes, and a comic as someone who could make you laugh without telling jokes. Like, you laughed at John Ritter's reactions to his roommates on Three's Company (did I just date myself?), and that would make him a Comic. You laugh at George Carlin's Seven Words You Can't Say On TV, and he's a Comedian. So there is a distinction, even though they're somewhat similar.

As far as what Nielsen said about himself, he's right. He's a deadpan actor. He says farcical things with a straight face, as if he's telling a simple story, yet we laugh at the absurdity of the story. That sort of puts him right on the line of Comic and Comedian, and simultaneously makes him both and neither.