<P> Another difference between NFL and CFL balls is that Canadian balls have two 1 inch (25 mm) complete white stripes around the football 3 inches (76 mm) from the largest diameter of the ball and NFL balls have no stripes at all . College football and high school football both specify the use of stripes, but only on two of the football's four panels (the ones adjacent to the laces). </P> <P> In American football, a team has four downs to advance the ball ten yards, while in Canadian football the limit is three downs . </P> <P> In both games, the ball is placed at a line of scrimmage, in which a player known as the centre / center performs a snap to start a football play . In Canadian football, the snap is required to go between the centre's legs; there is no such requirement in American football, but it is invariably done this way anyway, so the center is in position to block following the snap . The defensive team must stay a set distance away from the line of scrimmage on their side of the line . </P> <P> In Canadian football, the distance between the line of scrimmage and the defensive team is a full yard . Because of this one - yard distance, teams will tend to gamble on third and one or third and inches . If a team has possession within one yard of either goal line, the line of scrimmage is moved to the one - yard line . </P>

Why are there only 3 downs in the cfl