What are both FMN & NFM and are they equal or are they different? If they are different what makes them different?
FMN: FM narrow
NFM: Narrow FM
So they are probably the same.
I don't think having an FM category works, because that is simply the mode
Standard FM is still used by most hams, NOAA Weather Radio, Marine, Part 90 Low Band , and some UHF Part 90 (I think).
There's not really something called 'standard' FM because some particular bands have specifications that differ.
No - FM is a mode. NFM (and WFM) is exactly the same mode. The extra letter indicates the bandwidth in general terms. FM means absolutely nothing at all without the deviation, in the same way people mis-label AM. LSB, and USB are both variations of the AM mode - even though my transmitter has all three switches.
FM is the mode that all the ones we're talking about are. Clearly, broadcast and narrow bandwidth FM are different, and a broadcast receiver isn't much good at receiving the tiny deviation a comms channel has - but they are BOTH FM.
FM was the original FM mode? That's like stating that English was the first English. We're talking about the difference between the English spoken in Liverpool and Suffolk. The AM equivalent could then be Irish, with a north and south variation.