The difference is the ergonomics and most importantly, the motor. The XP has a more powerful motor. From Detailers Domain: When updating the 7424 to the 7424XP Porter Cable kept what makes the 7424 great polisher, specifically the mechanism behind the random orbit, while at the same time improving on the design. They have upped the max. OPM from 6,000 to 6,800, and gave it a more powerful motor so that you will get the same great results, just faster. They have also given it a more durable power switch and tweaked the Ergonomics to make this polisher more comfortable which gives you more control over the tool. So if you are in the market for a great polisher you can't go wrong with the new and improved Porter Cable 7424XP!
