So, the current factors that separate CFB from NFL Minor Leagues are:
1. Players are nominally students.
2. Players can't be drafted until three years out of HS.
3. The rules are a bit different, this is eroding quickly.
4. Winning your conference means something usually.
5. Larger stadia often as not in CFB, at least with the elite teams.
6. Quite a few teams are pastries.
7. We still have bowl games for 6-6 teams, and worse.
8. CFB relies heavily on "donations".
There are a few more I suppose.
Differences that have gone away are pretty clear,
1. You can draft juniors now.
2. CFB has a playoff similar to the NFL.
3. Colleges have mostly figured out a specific set of courses that keep a player eligible that are creative.
4. Players get paid, a lot in some cases, nothing in many cases.
5. ...