The STI PPP is just an STI with a prodrive ecu , fuel pump and exhaust upgrade. It does not include any suspension changes as standard, although they may be specified as an optional extra.
The WR1 is 320 ps or 216 bhp and came with a slighty higher state if tune than the sti PPP of the same model year, but it also included different wheels and suspension and some extra WR1 decals and unique (at the time) light blue body colour. The forn grill was also different incorporating a wire mesh effect.
The WR1 does not have a significant performance advantage over a sti ppp and in fact the following years STI MY 05 came with a wider track and uprated dccd which the WR1 doesn't have and is the one to get.
Frawls