My 50 cents:

Pornography and art are utterly mixed terms... pornography is representation you would not consume in public spaces or leave on your coffee table when the in-laws come to visit... this pornography may or may not be art. Its requisite subject matter varies by time and place but in the West today it typically involves genitals displayed in anticipation of or in the prosecution of sexual acts represented in such a way intended to prevoke sexual excitement. I would extend it to weirdness like persons licking toilet bowls or stepping on bugs in a prurient manner... again stuff you would not peruses pictures of on a crowded subway. I have been places in the world where a Sears catalog is most decidedly pornography... certainly representations of even non-sexual violence can be termed pornographic despite the origin of that word.

Erotica is pornography you can leave on the coffee table when your friends visit but might put away when your mom visits... depending on what your mom is like.

As for Art... IMHO it is presumptuous for some one to judge IF something is art but reasonable for ANYONE to judge if it is GOOD art. Something requires only a single nomination to be art as far as I am concerned... any other criteria seems unsustainable. I think that purveyors of simply pornographic material do not feel compelled to make any artistic claims in the West now. Even when they were required to in order to avoid sanction it was clearly a transparent ruse. Yet a third-party may nominate as art something that was made without that intention... I believe this is self evident. Once someone claims a thing is art all one can debate is whether it is good art or bad art.