The difference?
A whole bunch of marketing B.S. They just want you to think you have to have it. Maybe there are M/L scopes out there that offer more eye relief, but there are rifle scopes that claim to offer that as well, and that is an individual thing in my opinion that will vary person to person anyway.
A good quality rifle scope will perform just fine.
There's probably a difference in the ballistic plex models that base the spacing on the average drop of a muzzleloader rather than using rifle ballistics