First up chap.... Welcome to the boards!
Secondly best make an intro post before the mods have a subtle word in your ear
To answer your question.... there isn't any great differences between the 2, the accuracy from the pro will be alittle better out of the box, thats about it.
What you will find is that if you start to upgrade it it will be harder to gain the same fps levels from a shorter barrel than you will from a longer one..... the answer to that is do what I did to my Gspec and drill out the front and run a longer barrel into the silencer, after that you'll basicaly have a pro in a Gspec body.... simples!!
Theres other differences but they are mostly cosmetic rather than performance related