Spring-powered airsoft guns are single-shot devices that use elastic potential energy(EPE) stored in a spring to compress air to launch an airsoft pellet down the barrel of the gun.
Automatic electric guns
Electric-powered airsoft guns typically use a rechargeable battery to drive an electric motor, which cycles an internal piston/spring assembly in order to launch pellets. Automatic and semi-automatic operation is possible which gives these guns the popular name "automatic electric guns" or AEGs.
Hybrid Airsoft guns are the newest type of airsoft guns on the market, debuting summer 2006. Hybrid airsoft guns are basically standard AEGs with a "little extra reality" built in.
Low powered electric guns
KWA selective fire "Boys" Colt Commando electric rifle, approx. 3/4 scale, pictured with .12 gram Crosman ammunition and Cybergun
Called low powered electric guns (LPEGs) to distinguish them from the original, more expensive and more powerful AEGs even though their mechanical/electrical design and operation is similar.
Medium powered electric guns
Some companies - like UTG with their popular MP5 and AK-47 models - have improved their quality to such an extent that some models are now considered simply as mid-ranged AEGs that are more affordable but still reasonably effective.
Electric Blow Backs
Electric Blow Backs, also known as EBBs, are cheap electric guns, mostly modeled after real world pistols, which typically run from four AA batteries or AAA batteries.
Recently, the company UHC, well known for its spring guns, began manufacturing a range of electric guns in miniature size that fire only full automatic.
Automatic Electric Pistols
Automatic Electric Pistols, abbreviated AEPs, were first introduced by Tokyo Marui in 2005 with their Glock 18C (followed later by a Beretta 93R model).
Classic airsoft guns are usually older variety airsoft guns which are gas powered. Unlike the gas pistols of today, they can run on either an internal tank using conventional airsoft gas or use an external CO2 tank much like a paintball gun.