It varies by manufacturer and there is some overlap. With some types of guns the difference between full size and compact is noticeable, not so much with others. Individual tastes and skills vary too.
Glock for example makes 4 different size 9mm frames, 5 different slide lengths. I can see the long slides on G17 frames for target shooters. But for any type of carry the standard G17 just does nothing for me. They call the G19 a compact, but to me it is their full size pistol, the G17 is extra full size and offers no advantages to me. I understand that others prefer the G17. I look at the G26 as the compact and the G43 as subcompact. Glock doesn't see it that way.
But when I actually shoot the guns there is zero difference between G17 and G19 to me. And the G26 is close enough at typical ranges to not matter. I only shoot the bigger guns slightly better when ranges get out to 15-20 yards where shots are unlikely.
