[vindicareassassin]

SNAKE is part way to a correct answer

Apart from the barrel length the G-Spec has an intergrated silencer which actualy does function and I know is thorny ground for those who live in the US. The other differences are that the G-Spec will always slightly lag behind in accuracy due to barrel length and fps for the same given spring, all other things being equal. The other major difference is just a cosmetic one, in that the BAR has a tapered barrel and the G-Spec has a bull barrel( same diameter along its length)

One thig worth mentioning is, with a little modding the G-Spec can run a full length barrel (upto 480mm) if you run the barrel through the silencer.