What's the difference between an exhibitionist and a voyeur?

One is watched, the other watches. In practice most people at a play party are doing some of both, and the two are what make public spaces work at all.

The word that matters for both is consent, and it runs in both directions. Everyone in a well-run venue has agreed to be somewhere things happen, and every venue has strict etiquette about it: distance, silence, no phones, never interrupt.

Neither term describes anything involving people who haven't agreed. That isn't this, it's a crime, and the community treats it that way.