Personally, I don't see a difference between porn and erotica in general. Originally, I thought porn meant Live-action sex while erotica was written or drawn sex...
...It's all just sex.
Now, in my opinion, works that have a lot of overt sexual content with bits of plot here and there can be both called porn or erotica, interchangeably. Sure porn phonetically is more blunt and erotica is more flowery, but it's really the same.
I guess they are marketed differently, kinda like how a razor suddenly becomes 'feminine' with a pink handle even though it's used to cut hair, or soap becomes 'masculine' with a black packaging even though it's used to wash. It's all the same. The classic 'a rose by any other name (would smell as sweet)'
That said, people really need to loosen up about sex. Seriously.