I believe the 105 is a roster limit or eligible to come into a game. Again, I don't know this for fact but I believe you can have as many as you want "on the team" but only 105 are eligible to come into a game and only 85 can be on scholarship.105 is camp number…85 scholarship players and 20 walk ons. FBS is 85 scholarship limit. FCS is 65 if I remember correctly, and they’re able to have 95 at camp. I can’t remember DII numbers.
I could be mistaken, but I believe schools may be able to have as many as they want on the roster? Back in my day we had somewhere in the ballpark of 120, more than there were lockers, as is the case at a lot of schools. I wouldn’t be surprised if some schools have anywhere from 130-150ish, the later being DII, NAIA.