Similarities, shared history and subsequent differentiation
editRugby Union and American Football are both forms of "Running" football, descending from the Rugby School - where the ball is allowed to be carried in the hands of players, in contrast to Football (Soccer) where this is forbidden. The Basic concept, getting the ball beyond your opponents end of the pitch through a combination of kicking, passing and running with the ball are the same. Due to the many differences in other rules though, today there is only a superficial similarity between the sports. As such, very few players have achieved success at a high level in both sports.
The three main differences are in how play is continued after a tackle, whether players in front of the ball are off-side and whether players without the ball are allowed to be tackled. These different rules have dramatic repercussions to tactics, player safety, player size and shape and skills and are discussed below.
Scrums and the scrimmage
editIn the early, largely unwritten rules of Rugby as first played by footballers in America, contradictions in the rules meant that the ball was often trapped in the middle of the scrum (a physical pushing contest between a set of opposing players) , making for an unpredictable, slow and messy aspect to the game. In the uk, they solved this by excluding any scrummaging players from the off-side rule, allowing player to heel the ball back to a player behind the scrum.
On the other hand, in America (unaware of the rapid evolution of the game in the UK) it was decided to get rid of the scrum altogether, replacing it with what is known as a scrimmage where the ball could be quickly reintroduced into open play uncontested. --explain scrimmage--
Later, in Rugby Union the loose scrum (a scrum formed after a tackle) changed to a ruck - now formed immediately after a tackle, allowing the offensive team to quickly resume an attack provide. --continue--
--props vs guards--