All art is craft, but not all craft is art. The difference is whether it serves that critical function of art, which is to encode an emotion or thought fundamental to the human experience, and communicate it to another human being. It is a quantum quality. If someone gazes upon your firefox and says, "eh," then it is craft to them, and if someone else gazes upon the same firefox and feels a tugging in their chest, feels movement and fire and something that just reaches through them and pulls, then it is art. It depends upon the observer. Once you have made it, whether or not it is art is entirely out of your hands. It is, in fact, independent of your will whether or not something is art. You craft, and hope that what you have crafted is a good enough vessel to communicate, to one other person, what you wish to express. I think this is what all artists do.