Rule differences:
1. Field is smaller - only 50 yards long.
2. Field Goal post is about half as wide - 9 feet.
3. Only 8 players per side on the field.
4. Rosters only allow 20 active players
5. On defense, pass rush is restricted. Only 3 lineman and 1 (Mike) linebacker can rush until either the QB scrambles, or he pump-fakes. No stunts are allowed.
6. The Jack linebacker cannot rush, and cannot drop into deep pass coverage. He has to stand near the line of scrimmage until "released" by the QB. If there are no short routs and he doesn't get a pass block, he is dead weight. In essence, it is 8 on 7.
7. The defense has 3 DBs that can do any type of coverage. The offense has 3 WRs that are unrestricted.
8. The offense is allowed to have 1 player in forward motion. This is usually a fast WR sprinting towards the line of scrimmage (making it tougher to cover him).
9. The lock does not stop except for scores, except in the last 60 seconds of each half. In the last 60 seconds, the clock also stops on incomplete passes and out-of-bounds.
10. There is no punting. FGs are usually returnable.
11. There is a "rebound net" - kickoffs and FGs that don't go between the upright bounce into play, and are live. Either team can recover them.
A typical game total is about 98. Home field advantage is worth about 1. Scoring is typically 22% in Q1 and Q3, 28% in Q2 and Q4. Most games see 1 or more onsides kicks (and I've seen a game with 8 onsides kicks).
The "7" is worth about 15 cents - always buy onto and through it for 10 cents.
The "3" is worth much less than in NFL/NCAAF (due to the increased difficulty of kicking FGs).