Here's one of the result of a 2 second google search:
Click on each model for specs.
I want to get a glock 40 what to get what does the numbers and letters mean
G22 = Full Sized Frame
G23 = Compact Frame (My personal fav.)
G27 = Sub Compact Frame
G35 = Full Sized Frame, Long Slide
Any model with a "C" is Compensated (vented barrel to relieve recoil)
Models marked "SF" are Slim Frame(d) and offer better ergonomics on full-sized pistols.