I guess things are quite different in your place, Steelmagic. Here, in my part of Europe, things are like this:
- CO
2 is not the medium of choice in majority of cases. Traditionally, it was used with some handguns or (sniper) rifles, but seldom there were restrictions on CO
2 usage, at least when it came to handguns specifically. Few years ago, new generation of CO
2 powered assault rifles started to make waves on the market but at least to my knowledge, they are still not that popular. The price and more demanding maintenance compared to electric ones play huge role here.
- Other gases are so called green and red gas. Red is stronger, but both are weaker than CO
2 cannisters. Again, handguns and sniper rifles, with no real limits on usage I'd be aware of.
- The tool of choice for most of I know here is however AEG or Airsoft Electric Gun. A battery serves as a power source for electric motor that with the help of some gearwheels runs a cylinder that compresses air which in turn sends the bbs flying. As said, most of people I know use some sort of AEG unless they are sniping and most of AEGs are assault rifles. So yeah, automatic airsoft guns are pretty much standard here.
The best batteries used to be Ni-MH, but few years ago prices of Li-Po (which are generally smaller, hold more charge, last longer) started to go down and if I understand correctly, Li-Po is the new Ni-MH these days. Sadly, haven't been playing airsoft for years now.
- And I forgot about spring powered ones: well, spring is used in handguns, shotguns, rifles, sniper rifles and some assault gun replicas, but not for actual automatic firing. Generally, only sniper rifles and shotguns (kinda) are the ones to utilize spring to a "competitive" degree, other I mentioned boil down to under-powered replicas meant for the under-aged OR as a cheap replacement if you really can't get anything else. I mean, you can easily get together with some friend you know and you all use spring powered handguns, why not. But if there's even just one guy wit automatic aeg, well, he has an obvious advantage. But I do imagine spring powered CQB battle could be quite entertaining, even though I never had the pleasure of participating in one.
As for BB guns and BB pellets - yeah there was some confusion on my part too here. But I do believe the confusion is due to the fact
"air guns shooting lead pellets" were/are often called BB guns. In airsoft, BB is a name for pellet we use, but those are round, PLASTIC pellets. So in some ways, airsoft guns ARE bb guns but...not those kind of bb guns, I guess.
Also, I think it's almost impossible airsoft would be illegal in Korea. I might be mistaken here, but I do think you have quite a lively scene there. Well, I know for sure Japan, Taiwan, Philippines and China, possibly Vietnam, have it, though there are bound to be some difference in local laws (for instance, Japan is very strict on pellet speed restrictions, where here in Europe we don't give a damn). Ok, China produces lot's of AEGs, but I'm also not sure on the actual airsoft scene there. They had some crap going down over "gun replicas that look like guns" few years ago.
But anyways - I'd be glad if I could help with your question even further, being an airsoft player myself! Though as mentioned earlier, I'm semi-retired now so some of my knowledge might not be up to date. And also I never was some pro player. I only have, like, 2 assault guns at home these days.
Dammit, I need to fund a job. I swear, when the money starts flowing again, off to imaginary battle we go!