The number the player wears on their back during the start of a rugby match correlates to the position they are playing, so people often interchange the position name with the position jersey number. Numbers larger than 15 are substitution numbers and could be any position. Another thing to note about rugby is that positions are not divided into offenders and defenders because ruggers must play both offense and defense.
The most basic division of positions is between forwards and backs. Some of the differences between the forwards and the backs are that the forwards do a lot of the grunt work including scrumming, line-outs, and most of the rucking, and the backs run more with the ball in hand and run plays off of scrums and line-outs.
1 - Prop (loose-head) - left, front row of the scrum
3 - Prop (tight-head) - right, front row of the scrum
2 - Hooker - hooks the ball in scrums & usually throws ball in line-outs
4, 5 - Lock - stabilizes & powers the scrum
6,7 - Flanker - can break off the scrum quickly
8 - 8-man (Flanker) - holds the ball in the scrum
9 - Scrum-half - link between forwards and backs
10 - Fly-half - distrubutes the ball to the backs
11, 14 - Wing - fast, outside finshiers
12 - Center (inside) - aggressive, hard hitting inforcer
13 - Center (outside) - aggressive, hard hitting inforcer
15 - Fullback - last line of defense
Dicitionary • Positions • The Pitch • Game Objectives • Rules