It's a distinction I hadn't really thought about before now, but it does seem to be how I've been mentally distinguishing the two.

"Lever" was mostly facetious, though I'm sure I've seen see-saws used in a lesson on Simple Machines.
Hmm. "Seen see-saws". My internal grammar software nearly threw a wobbler on that one.

(Oh, that? I'd assumed it was more Obligatory Dragon Humor.)