The P380 is actually built lighter than the R380. The recoil spring seems lighter to me, but that is subjective.
When all else fails, read the book. The manual specifically says not to use +P or +P+ ammunition in the R9.
Right below that it says to use 380 ACP or 9mm Kurz in the R380. Nothing is said about +P but since there are no industry specs on it, I would not mention it either.