Other than organizational, RMSS and RMFRP are approximately 95%-98% identical to one another. RMFRP essentially fixed some errata when they re-organized things.
If the old ICE had not rebranded it and changed the trade dress, you could call it the same system.
As it is, the common method of referring to either and/or both is RMSS/FRP which means that we (the current ICE) consider it close enough to call it the same system.