Yes! They Certainly do and it has become a big topic around the ATP and WTA committee. Each week having to adjust to a new ball for a new tournament on sometimes a new surface can be exhausting. Plus it can't be good for your arm. Some balls are a little thicker, or bigger, or heavier, or bounce higher or more felty. The Australian Open plays with with Dunlop, The French Open Plays with Babolat, Wimbledon plays with Slazenger, and The US Open plays with Wilson