Big powerful guys whos primary job is to tackle, win possesions of the ball and provide strong power to scrums
Lighter and faster guys who gets the ball and tries to gain much yards as possible by breaking the line and going through their defence.
Only the person who is carrying the ball can be tackled and the tackle has to be below chest level. As soon as tackle happens and other team is close by then the ball carrier has to release the ball.
Ruck is a phase of a game where players compete for the ball after a person is tackled. Players must drive over the ruck to take possession of the ball.
Mual is when a team bunch up to protect the ball and drive through the other team. There must be least 3 people ball can be passed on to other people from the back.