They're exactly the same, as required by the supersport homologation rules, so no increase in compression.
Valve lift is also the same on the R and RS.
RS's run (up top) different cams (shorter duration, to close faster
) and different valves (same size different material) RS ports are fully open to 36mm where R's are still around 33mm (easy gains for an R...)
[Edited on 31-3-2005 by Mr_S]