On Ice

Referee:
Wears red/orange armbands.  Supervises the game and is in complete charge. Starts the game, calls penalties, determines goals and handles face-offs in the defending zones.

Linesman:
Two are used.  They call offside, icing and handle all face-offs in the neutral zone.  Also help break up battles between players. They do not call penalties, but can recommend to the referee that a penalty be called.

Off Ice

Goal Judge:
One sits off-ice behind each net and indicates when the puck has crossed the goal line by turning on a red light.  The referee can ask his advice on disputed goals, but the referee has final authority on whether or not a goal has been scored and can overrule the goal judge.

Scorer:
Determines which player scores and credits assists if there are any.  He may consult the referee, but the scorer is the final authority in crediting points.