Model confusion?

Hey everyone,

I'm wondering what is the difference between a normal 1. Subaru forester Gt (Australia), 2. s/bt ( car 1&2 of the first series ) 3. of second series the s/bt Sti 4. of the second series the s/bt sti 2

I know there were engine differences (very limited knowledge about them) but were there also suspension differences etc ?

Sorry for the very confusing post