On Snap-On:
F means 3/8" drive, while FH means 3/8" with comfort handle
An L will mean long, and a second F will mean flex-head
So an F80 means just a regular 3/8" ratchet, but FHLF80 means a long, soft-handled, flex-head.
They'll also add B for bent handle, K for stubby, and X for locking flex...