American football
Football games last for a total of 60 minutes in professional and college play and are divided into two-halves of 30 minutes and four-quarters of 15 minutes. High school football games are 48 minutes in length with two-halves of 24 minutes and four-quarters of 12 minutes. The two-halves are separated by a halftime period, and the first and third quarters are also followed by a short break. Prior to the start of the game, the referee and team captains for each team meet at midfield for a coin toss. The visiting team is allowed to call 'heads' or 'tails'; the winner of the toss is allowed to decide between choosing whether to receive or kick off the ball or choosing which goal they want to defend, but they can also defer their choice until the second half. The losing team, unless the winning team decides to defer, is allowed to choose the option the winning team did not select, and receives the option to receive, kick, or select a goal to defend to begin the second half. Most teams choose to receive or defer, because choosing to kick the ball to start the game would allow the other team to choose which goal to defend. Teams switch goals following the first and third quarters. If a down is in progress when a quarter ends, play continues until the down is completed.
Comparison of American football and rugby league
Generally, American football games last much longer than 80-minute rugby league matches. Because the field is reset after each tackle in American football, it is much slower-paced than the more hectic rugby league, in which play stops for only as long as it takes the tackled player to get back to his feet and return the ball to play. Another major difference is that only the player with possession of the ball may be interfered with in rugby league; defending players interfering with any other attacking player (and vice versa) will incur a penalty. Passing in the two sports also differs: while backward passing is common to both sports, in American football players are allowed to throw the ball forward in certain situations whereas in rugby league forward passing is always illegal. rugby league footballers have to kick the ball or run it forward to advance it downfield. To score a try or touchdown in rugby league, the player has to push the ball directly onto the ground once in the try zone, whereas in American football the player has to simply cross the line. American football also requires its players to use a large amount of protective equipment, including helmets, gloves and padding around the body, whereas protective clothing is much more minimal in rugby league, usually amounting to light padding (if any) and soft head gear (hard helmets being illegal). 
The rugby pitch and American football field are both similar in size with a pitch being 100 meters while a football field is 100 yards.