The Grip Frame area is "slimmer". I have both, 30 and 30 SF. A couple of years ago when Glock came out with the Glock 21 SF "Short Frame" or Slim Frame as many are calling it, the grip area was reduced to help those with smaller hands to get a better/ more comfortable grip. Let's face it, the Glock 21 is a big gun and many people who would like to have one, avoid it because of the size of the grip. Of course since the Model 30 is the same frame only shorter, the 30 SF soon followed. I really like the Model 30 and have several. 2 of them are SF's and seem to be a little more comfortable to shoot, even with my big mits. The difference isn't drastic mind you, but you can feel the difference in the comfort and bulk factors.