I know several people who write erotic romance, both straight and gay stories. Their sex scenes are, um, let's say explicit. Terminology is raw, with lots of oportunities to make use of it. Nudge, nudge.
By comparison, my sex scenes are tame. You might have to read 100 pages before you find one. Maybe 200! I'll tell you what happens, but the emphasis will be on their emotions. Romance, you know? Then again, if you're used to reading Dan Brown or Sue Grimshaw, the scenes are a bit lively. So let's say I write sexy romance.
But that's winthin the romance writing community. Outside of it, definitions are a bit less exact.
Scene: I am introduced to my neighbor's adult son, who is visiting.
Neighbor: This is our neighbor, Starr.
Me: (shaking his hand) Hi.
Neighbor: Starr's the one who writes the dirty books.
Me: Well, they're not really...
Son: Oh, you're the one!
Sigh. I guess that's me - the one who writes dirty books.