They are all very talented. My favorites include Tim Herron, Glen Day, Billy Ray Brown, Scott McCarron, Mark O'Meara, and various others who won't come to my mind right now. My opinion is that there is not a difference. Do they pay for their own travel and other expenses and so on. Thanks for all the great insights by the way.
Caddies are independent contractors with the player.
They all have different but similar relationships. Most are paid base salary plus a percentage of what the player wins that week. The percentages are negotiated and the caddie pays his own expenses. Their income is closely tied to how well the pro performs. Stewart should have his best chance at a U.S. Open.