[9secfirebird]

one uses gas and the other is gas-less, the gas-less one tends to splatter more unless you are using the right size wire and a good amount of heat for the speed you weld. the gas-fed mig can give you a cleaner weld. a gas-less one, once you get good with it, can be very handy, portable, and with enough practice, you can produce a real nice weld. mig works best with mild steel, exhausts and stuff like that, once you get into chrome moly stuff ya should really use a tig.