I read two rules quoted on this website that seems to overlap:
Rule 5, Section 1, Article 1:
The game is played by two teams of 11 players each. If a snap, free kick, or fair-catch kick is made while a team has fewer than 11 players on the field of play or the end zone, the ball is in play, and there is no penalty.
Section 5 Position of Players at the Snap, Article 1: Offensive Team
The offensive team must be in compliance with the following at the snap:
(a) It must have seven or more players on its line (3-18); and
(b) All players who are not on the line, other than the receiver of the snap under center, must be at least one yard behind it.
(c) No player may be out of bounds.
The first one says that the play can possibly start without all the players within the bounds. The second one says that the formation is considered illegal (penalty) if a player is out of bound.
The question is : what is the difference between an "out of bound" player and a player who is not part of the play to begin with ?
Moreover, it must have seven or more players on the line but the first rule implies that it is possible to have less than 7 players so it is another contradiction.
Is that a real overlap or I am missing something here ?