I would guess that eroticism is supposed to inspire creativity while pronography supposedly replaces it. So if the piece in question were to be presented to people while their brain activity is being monitored I would expect to see an increase of activity throughout the brain for eroticism while I'd expect a decrease or concentration of activity for pornography. Although I have no idea if that is actually the case.

Without reference to sexual stimulation this would include a lot of things that are not currently thought of as pornography, but that might actually be intentional depending on the reason why someone would want to ban pornography.