I thought GTI had a Audi FSI Engine with a turbocharger?? 
It does, and the "basic" terminology of the 2 litre FSI turbo lump is used in many VAG products, in both conventional layout (Audi A4) and transverse layout (Audi A3, S3, VW Passat, Golf GTI, Ed30, Seat Leon Cupra, Skoda Octavia vRS).
However, just like the older 1.8 20 valve turbo, which came in many different power outputs, there was a variety of "methods" used to achieve the differing power outputs. These ranged from simple ECU changes, all the way to completely different internals, like on the Mk1 TT 225PS, and the older S3.
Or at least thats what I was told. In SA here we get the FSI engine alone as an option and then the GTI gets the Audi FSI engine with some extra power etc?
Unconfuse me please
Same here, you can get the normally aspriated (ie non-turbo) 2 litre FSI, rated at 150PS, and then the turbo charged version, with power outputs of 200PS, 230PS, 240PS and 265PS.