200tdi and 300tdi turbo question...

Are the internals of the 200 and 300 tdi engine different?

I know the externals are different however im looking at replacing the cartridge in a friends 200tdi disco engine turbo and ebay only really shows 300tdi yet list as 1990-1999 which we know the 300 wasn't out in 1990...

Only other thing I can find is the 200 is a T250 2 and I think the 300 is a T250 4?

Thanks