This is something that I think about a lot, you cannot explain it in such simple terms because as already mentioned photography is such a diverse subject, It can be a means of documentation, advertisement, illustration or it can be a means of artistic expression. To me, real art should not just be something that is beautiful, but should also evokes some sort of emotion in the viewer. An artist who uses photography as his/her medium will visualise the image they want to produce...
(or maybe they wont, but that opens another can of worms- ie, is it only art if the 'artist' intended to make it, for instance, I have a beautiful book called Photo Trouvee,
http://www.phaidon.com/Default.aspx/Web/photo-trouvee-9780714845791 containing images which I would consider art, because of the context in which they are placed, although some might not because they are amateur photographs- Can art be produced without an artist?)
...and then use their skill and knowledge and craftmanship to produce that desired image, the artwork.
The trouble is that not all 'artists' have any technical or practical skills whatsoever. They may have vision, but do not have the skills to realise it, or vise versa.
I suppose a better question would be 'does the photographer consider themself an artist?'
I'm trying to come up with a better conclusion, but thats the best i can do for now