A sevens team is made up of 7 players who are two props, a hooker, scrum-half, fly-half, centre and winger. This differs from the normal 15 a side game which includes five more forwards and three more backs. Numbers on the back of jerseys in a sevens match do not correspond to a specific position as many players will be given the same squad number for the entire tournament.
Another notable difference between the two codes is the fact that a scrum in a sevens match is made up of 3 players whereas a scrum in the 15 a side game includes eight forwards. Since the field is the same size in both codes, sevens matches tend to be played at a higher pace.
In sevens matches, each half is 7 minutes long rather than 40 minutes in a 15 a side match. Halftime lasts for only 2 minutes in sevens which is why you usually see coaches giving a quick team talk on the field, rather than going into the changing rooms. Because of the amount of running each player must do, each team is allowed five substitutions rather than the eight given usually.
Another rule in sevens rugby is that after scoring a try, the conversion must be taken within 30 seconds of the try being scored, it is also taken by a dropkick, rather than using a kicking tee. This ensures that each game goes along smoothly and no time is wasted in order to gain an advantage over the opposition.
The team who scores a try then takes the kickoff; this allows each team to get a fair share of the ball in the short time they play. This is the opposite in 15 a side matches as teams take kickoffs tactically in order to gain some territory (which is a more important statistic in this code.) In 15 a side matches, a yellow-carded player will leave the field of play for 10 minutes, however, a yellow card in a sevens match results in the offending player leaving the field for 2 minutes.