let me explain the NFL it rules real quick.
we still start with a coin toss to
decide the first possession
if the team that wins the toss (and takes the ball) scores a touchdown. game, set, match, they win.
if they only score a field goal (3 points) the other team gets the ball.
If that other team scores a touchdown (6 points) they win. if they only score a field goal, the first team gets the ball and then it's sudden death (next to to score any points wins.)