No Tuck Rule - The Tuck rule is one of the most controversial rules in the NFL. In the NFL, if a passer brings his arm forward in a passing motion and then loses possession of the ball as he is attempting to tuck it back toward his body, it's considered a forward pass (and thus an incomplete pass if the ball hits the ground). In the UFL, it would be called a fumble either way.
Touchdown celebrations - Celebrations, individual or group, will only take place in the endzones and on the bench area.
Fumbling out of the endzones - If the ball is fumbled out of the endzone, it will be placed back at the spot of the fumble, pending which team last had possession.
Intentional grounding - A quarterback is allowed to intentionally ground the ball anywhere behind the line of scrimmage if he is under pressure.
Instant replay - All reviews will be viewed upstairs by the replay official and he will only have 90 seconds for review.
Overtime - Both teams will be guaranteed at least one possession. When a team scores, the other team will get a last chance to score on the next drive. Similar to the College football rule.
Officials - instead of the traditional black-and-white uniforms, UFL referees wear a red polo shirt with black pants.
Play Clock - While the NFL has a 40 second play clock, the UFL has a 25 second play clock, which results in more plays and maintains a fast pace quality of play.