I had to throw in my thoughts.
I think that porn is hard driven, physical. . .etc. sex.
Words like cock, prick, cunt, twat, pussy, even penis. Asshole, tits, cum, juices. . .always make me think 'porn'.
And that's okay! I like porn!
I think that erotica is sensual/intellectual. Just as graphic, but couched in softer terms. More prose, less pussy. Lushly written, descriptive emotional feelings.
How does he/she taste?
What does his/her skin feel like?
I do think that porn is harder to write well. I think it's too easy to get carried away with pronouns and loose the audience. You want to convey a sense of hot, sweaty fucking. Not just use slang/curse words.
I think erotica is easier to write. Describing emotions, senses, smooth actions . . .
And I think that they can both be incredibly sexy.