They are the same. I have used needle guns working in mill maintenance jobs. they are okay to prep rusty joints for welding (i prefer a mini grinder), but like Wayne says, they are noisy and they arent great for big jobs. I'm not sure how much air they use, as I have only ever used them on an industrial air supply.
Jordan, I think you might find sandblasting a better alternative. There is a Princess Auto Supply near me and they have a great varitey of sandblasting equipment for reasonable prices.
They may have a store near you.
http://www.princessauto.com
Not sure if anyone else has some thoughts.