i think their are 4.
the new garmin gps unit and inreach(2) a gps one and a no gps one and the mini.
new garmin was big and very complicated and not a lot worked.(yet)
garmin claims the inreach/with gps is a garmin unit, but its a delorme based machine(if a track is a route then its delorme). also WOW u can send 10 minute track points to the cloud. wow on a MC that coud be a 20 mile diamater search area. almost as bad for a fast hiker. or even longer if you want(??? an hour).
since all require the sky...i liked a good bread crumb trail, so when i dropped in to a canyon at least they new where i was last seen. this way i could be 1/2 mile from last ping.(no good)
good luck adding "routes to the gps unit(the older one) u need the web, u need it to work and convert tracks to 200 point routes.
my old delorme+gps unit sent a zillion track points up and delorme software let me add 'routes etc' to it
every 10 mins is stupid. (but to solve people from using the old units u can not get them off the could any more)
i bought the new garmin inreach but sent it back
just got the garmin/gps inreach lots of options work(not all)
i would get a garmin gps and the cheaper inreach(not mini if i was not to lazy to send mine back)