Gas Powered Airsoft Pistol
Gas powered airsoft pistol is the most available airsoft pistol around. It is powred by pressurized gas that comes in a form of green gas or CO2. There are 2 types of namely blowback or GBB, and non-blowback. Blowback means that the slide moves backwards and cycles every time you shoot until you ran out of bbs or gas. These are the most realistic in terms of function. Non-blowback airsoft has the slide fixed and does not move when shooting. These airsoft pistols has FPS ranges from 250-400 FPS depending on manufacturer and design. Some may use an adapter to hook gas airsoft pistols to a HPA tank to power it.
Electric Airsoft Pistol
Electric airsoft pistols or AEP are battery powered airsoft pistols. It uses an electric motor, gearset, piston and spring to create air pressure to shoot the bbs out. These are fairly fun to use but usually have lower FPS around the 180-250 range.
Spring Powered Airsoft Pistol
Spring powered airsoft pistols or some call it springers are also common. These airsoft pistols are usually the most inexpensive are usually used by entry level players. To operate one must manually cock the pistol for it to be ready to shoot. These are also often times used as props for budget film makers.