The answer I give to your question would depend somewhat on context, since there are so many variations of the terms. For example, Pivots, Pivoting Actions and Spins can refer very specifically to elements in the International Standard syllabus, which have one very localized definition. In a more generalized context, you might be asking about what kinds of qualities define a spin, a turn, a twist, or a pivot in terms of the action itself. That has an entirely different answer.

If you clarify which of these contexts you are thinking of (or perhaps even a third one that I didn't mention), I might be able to shed some more light on the subject for you.

Sincerely,
Jonathan Atknson www.ballroomdancers.com

You'll probably get a more knowledgeable reply than this one, but here's one distinction I myself had to unlearn regarding one difference:

I'd been taught to do a Nat Spin (part 4-6) like a pivot - a thigh-to-thigh rotation (sort of). When I got a qualified Int'l trainer, I properly relearned it as "swinging" the lady past me (with my own LF/hip rotation), then "picking her up" (RF heel lead, instead of sticking my right leg in her way as I had been doing.

There are other thigns we call "pivots", too - Rev Pivot in I-W or QS, for example, or repeated half-turn pivots down the LOD, or the Promenade Pivot Turn in A-W & A-FT come to mind. These don't use the trained swinging/reaching movements of a spin turn, as I understand (& do) it. Any correction welcomed.