One clear difference between art and commercial work is that commercial work is exploitive: the work may be high quality but the intention is to sell product or tickets. Art exists with or without ticket sales.
Twyla TharpDestiny, quite often, is a determined parent. Mozart was hardly some naive prodigy who sat down at the keyboard and, with God whispering in his ears, let music flow from his fingertips. It's a nice image for selling tickets to movies, but whether or not God has kissed your brow, you still have to work. Without learning and preparation, you won't know how to harness the power of that kiss.
Twyla Tharp