It's something of a semantic riddle for the creative person. Sometimes I couldn't care less about that defined difference; other times it tortures me to no end.
I suppose that when I moved to California (thus, selling out as a "real" artist to earn money as a commercial artist), the philosophical 'art or design' issue began to haunt me. Never before had I needed consider any other creative eyes (or opinions) besides my own; now, working commercially, I often require the approval of others during the process.
I am often fascinated with artists who have made a career of straddling that proverbial line; making the 'art or design' argument that much more complex (Warhol being the most obvious example). Above is an image of one of my 'long-term-MUST-purchase-eventually' consumer shopping list, which I just won on Ebay last week; 1983 Talking Heads LP by Robert Rauschenberg. I can finally cross that one off of my list (and start looking at the other items on said list).
(Note: I reserve the right to alter/completely contradict/discount my opinions at any moment...)