I don't get people saying the user score is irrelevant, if it was irrelevant it wouldn't be there in the first place.
They both have the same score so if we're going to be technical and unbiased they're both equally good albums and have the same amount of critical acclaim.
To answer the OP I think that ARTPOP has more dance music and managed to fit in a couple ballads. PRISM is just ballad after ballad. I don't understand how a fan of pop music wouldn't get bored of a slow album.