i thought RED meant it was a faster model,
but i guess it doesnt 
LL 
Indeed most people think that the "red I" mk4 golf is a turbo, Not true as said thay all have different badges regardless of being turbo or not!! 
For diesels see below. I am certain of that.
TDI (All Red) is a 150bhp Diesel Engine
TDI (Red D, Red I) is a 130bhp Diesel Engine
TDI (Red I) is either a 115bhp or 110bhp Diesel Engine depending on the Year
TDI (All Silver) is a 90 bhp Diesel Engine