Isn’t prep more like a prophylactic, as opposed to a a vaccine?

I’m more familiar with malaria, where the preventative medicines are currently more effective than the vaccines.

The analogy to malaria is pretty on point. Pre-Exposure Prophylaxis (PrEP) is, you nailed it, prophylactic. It's not as good as a vaccine would be, and it's not as cheap as a one-and-done shot, but we've gotten to the point where you can get one shot every six months (lenacapavir) and, it's 99%+ effective at preventing infection. And, much like with malaria, the prophylaxis works— there is currently no HIV vaccine that reliably prevents infection.

"Prophylactic" is a broad-enough word to encompass vaccines, as well, so I'm not sure what you're getting at. It just means something that defends against disease.