Per a salesman at my local Porter Cable store, it's just that it does not come with the "Buffing" pad.
I was able to find a really cheap price on a 7424 kit in my local area. I paid $129 out the door for everything, including an extra white pad.
The results I've gotten with this tool is remarkable! Just make sure that you use the correct products for the job needed.
I use Meguire's #1 #2 #9 and #7 glaze. My wife's 1997 4Runner looks just about new. The two coats of Zaino Z-2 made it even better.
