This is the same as the old saying about teaching someone to fish versus given them a fish.
To steal is to make it your own, to so thoroughly understand it that you can move it forward as if it was always yours. To copy is to simply have it for today without having the understanding it takes to have had the idea in the first place, and so you can't go forward.
It wasn't Picasso, but T. S. Eliot. And "simplicity is the ultimate sophistication" (another Jobs favorite) was said not by Leonardo, but by William Gaddis.
http://www.youtube.com/watch?v=CW0DUg63lqU