For the uninitiated, rugby and American football can look remarkably similar to one another. Yes, some differences are immediately apparent — rugby is much more often a "free for all" compared to the rigidly structured plays one finds in the National Football League in the USA. That said, the similarities aren't a coincidence: both sports share a common ancestor, a sport developed by the British in the 1800s. Over time, the two games diverged, the modern rulesets emerged, and both pursuits developed their own passionate and dedicated fan bases. Today, rugby remains far less popular in North America than in other nations around the world, and American football is largely just that: American.
Even so, there are plenty of intriguing similarities to note between the games alongside their differences. Are you curious about how the mechanics of the two games compare? From the size of the playing field to the way scoring works and 
even how the game allows players to come on and off the field, you'll find there are plenty of links that tip us off to the common origin for these games. Settle in and get ready to learn about how to tell these two cousins apart.
Understanding the rugby pitch and the football field
Looking at the playing field is the easy place to begin making our comparisons. At first glance, especially from a distance, it can seem like the fields are almost identical in size. To a certain extent, that can be true — but the core difference here is that a rugby pitch is somewhat larger than an American football field.
For the Americans, whose sport still favours the Imperial system, the playing field is 100 yards wide with a 10-yard end zone on either side. The field is 160 feet in width, which for those doing the maths works out to about 53 yards and change. A rugby field is similar, but uses a 120-metre total length (goal areas included) with a 60-metre width, yielding a wider, longer space.
While the yard lines in American football are largely purely to mark distance, rugby field lines influence the action of the game in some ways. Each play in American football centres around four attempts to move the ball a complete 10-yard increment. At the start of a rugby half or during a restart following a stoppage, the ball must travel at least 10 metres. While there are not many differences between the playing fields, the subtle differences can make a difference.
How do the players correspond to one another?
Comparing rugby players and football players might seem easy at first because they share many similar names, but the functions are quite different. On the rugby field, a team puts out 15 players — and that's it for the game! Those 15 positions make up the entirety of both the offence and defence for a rugby team, and they must play differently based on who currently has possession of the ball.
In football, of course, the teams break down into a variety of units. The offence goes out on the field with possession of the ball, while the defence takes the field to keep the opposing team from moving the ball. Special teams come out for plays such as field goals, kickoffs, and other such plays. Each of these units puts only 11 men out on the field, so there are fewer active players in a football game versus a rugby match.
While the names don't line up, some of the duties for the players do; for example, the quarterback in football is meant to be a leader, pushing the team forward and controlling strategy to some degree. A fly-half in rugby is similar, coordinating the back line and handling the ball with increased frequency. However, overall the player positions are very different from one another due to the dramatically different styles of play between the two games.
Moving the ball: where the big differences lie
In football, the clock stops all the time: when the ball goes out of bounds or when a pass isn't caught, and so on — but in rugby, the clock doesn't stop except for serious injuries. This is key to understanding the difference between how players move the ball. Rugby is much more of a free-flowing game, built on continually contesting the ball back and forth between the two teams. Stoppages are discouraged to keep the teams pitted against one another. Football takes a more rigid, structured approach to moving the ball.
In football, a play ends whenever the ball or the player carrying the ball hits the ground or cannot move forward anymore. Running with the ball and the forward pass are the primary means of gaining yardage. In rugby, players cannot throw forward passes at all; instead, they can only pitch laterally to team-mates. Throwing to players behind oneself is also permitted. Kicking the ball is also an important component of the movement, and players do not have to run straight forward; they have full freedom of movement around the pitch. As a result, rugby is far more fast-paced, with frequent changes in possession. American football, on the other hand, is a slow and methodical game punctuated with bursts of action.
Breaking down the mechanics of scoring
To score in football, the ball must reach the end zone or pass through the upright posts at the back of each end zone. A touchdown is worth 6 points with an extra kick for 1 additional point; field goals, which teams may attempt from any point on the field, are worth just 3 points. Other scoring opportunities exist, such as the safety, but are rare. To score in this game is simply a matter of getting the ball over the goal line, but the goal area in rugby works differently.
In rugby, a scoring play is called a "try" and occurs when a player enters the opposing team's goal area with the ball and touches it to the ground. A player can score a try on a ball that enters the goal area by another means, such as kicking, if they reach it and press the ball into the ground. After a try, teams may choose to kick a "conversion" through the goal posts on the pitch at spot 90 degrees from where players scored the try. When successfully executed, it is worth 2 points. Afterward, play restarts via a normal kick for the opposing team.
Where are these games most frequently played?
Both sports boast a significant degree of popularity, although American football remains mostly confined to the States. Countries such as Canada and Australia have developed their own versions of football, which are at times highly similar and very different from the American version. The National Football League is the primary sanctioning body for games in America, with some smaller amateur leagues staging games as well. Though the NFL has considered expansions into Europe, so far, no teams from non-American regions have competed at the highest level.
Rugby features a much larger number of leagues, with regional teams competing in many areas around the world. Overall, the World Rugby organisation acts as the primary arbiter of the rules and is responsible for putting on the Rugby World Cup. National federations oversee competitions and organise the standings for these teams. For example, the famous All Blacks a part of New Zealand Rugby, which governs all the games that take place in NZ. Similar structures are in place in other areas where rugby is popular, such as South Africa, England, Australia, and many more.
Will you find yourself turning into a fan of both sports?
Once you start sorting out the rules between the two games, it doesn't take long to see that while they may have come from the same place originally, they have long since diverged into unique pursuits with very different philosophies towards the game at hand. Even so, there's something to love on both sides of the pitch: the finesse and skill necessary to throw a long "bomb" pass in American football is just as impressive as the raw strength and endurance it takes for rugby players to last through a whole match. Whichever you watch, it should now be easier for you to understand what's going on — even if you mix up your terminology from time to time!
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