You figured out the designations just fine. They are RN for round nose and FP for flat point.
I have yet to try the RN, but have almost used up a box of the FP in .45. They are very good value for the money and I plan on buying many more boxes. Good QC on them and they seem to be very consistant in weight.
As for application of the two types, I don't know ballistically but the RN tend to feed easier in all types of guns due to the round nose. I've been told that the 1911s don't like the FP at all and won't feed more than 20%. I have a Glock and haven't had a problem yet. If your gun is choosy about the ammo shapes it will feed, I would try the RN first.