What's the difference between a submissive and a masochist?

A submissive hands over control. A masochist enjoys pain. They're answers to two different questions, which is why plenty of people are one without being the other.

A submissive who doesn't want to be hurt is completely ordinary: the appeal is following someone's lead, and that can be entirely gentle. A masochist who stays in charge throughout is equally ordinary: they want the intensity, not the hierarchy.

The pairing is common enough that the words get used interchangeably, which causes real problems in negotiation. Saying "I'm submissive" and being handed a cane you never wanted is a direct consequence of the confusion.