hi dino, all the football games had their roots in a street game that was played by all the men from one village against all the men from the next, the object was to get (i think) a pigs bladder to the other side of the village. there were many injuries and sometimes deaths and a lot of fighting. from this i believe soccer came into being. then during a game in the high school named RUGBY someone picked up the ball and the game came into being. i think it's the same guy who then took the game to ireland, australia then america, giving each their own rules. there is also two similar yet different rugby disciplines, union and league. in the UK league is played mainly in the north of england, whereas union is played mainly down south, and of-course in wales scotland and ireland, where each also has a league side. league is also a big game in new zealand and australia.
the main differences between rugby and american football, is that you are only allowed to tackle the man holding the ball, when you have a touch down in rugby, you actually have to touch the ball to the ground. if a substitution occurs that player stays on, in football i believe that players are put on for certain plays then taken off till the next play. and of-course you play the 40 minutes of each half without stopping for commercial breaks or time-outs. you dont just need to be super fit but also have stamina.