While college and pro football may share a number of similarities, there are some significant rule differences between the two. One major difference is in the length of season for both college and pro football. While pro football features a four game preseason, 16 game regular season, and four playoff rounds, the college football season only consists of about twelve games with a bowl game for those teams that qualify. This difference is often cited by NFL rookies who hit a proverbial wall near the middle of their first pro season.
As well, during college football games, there is a different way in which tie games are dealt with than in the NFL. In the NFL, a tied game in regulation time goes into 15-minute overtime. The first person to score in this overtime scenario is the winner. However, once this 15-minute overtime is complete and no one has scored, the game is called a tie. In college football, they have developed a unique way of dealing with overtime. A tied regulation game goes into an overtime period, which consists of both teams receiving the ball at the opposing 25-yard line. There is no clock, so time is not a consideration, but getting a touchdown is important, because after a possession, the opposing team gets the ball. If they score more points than their opponent in the second possession, they win the game. If neither team scores or if they match points, it goes into a second period. By the third overtime period, teams have to go for two point conversions, instead of extra points, in order to prevent the game from going on for an indefinite amount of time. However, every college football game is decided without the option for a tie.
A third way in which the college football rules are different from the NFL is the two-minute warning. At the end of each half in the NFL, the clock automatically stops at the two-minute mark as a free timeout for both sides. However, the college football rules do not include a two-minute warning and are geared towards keeping the game moving except for injuries, time outs, and other extenuating circumstances. New rules in the 2006 college football season have made good clock management even more important, with the clock starting at the beginning of each possession and stricter rules on when the clock stops on plays that go out of bounds.