yea i know at all the fields i play at its "rouge spear" rules, which is basically a hit to any extremidy renders it useless, but you may still play "disabled" a hit to the head or torso is an instant death, and body armor (helmets, plate carriers etc) can take one hit then are considered broken and offer no protection. other then that mango hit it about nail on the head, fps and engagement limits is the big thing, i prefer not to have a 450fps AEG pinted up my nose from 3 feet away
as far as differences, as far as safety its pretty similar, only in airsoft most of the time you only need goggles once your 18+ as apposed to a full face mask. the play is generally the same though.