there are 2 referees on the ice and 2 linesman
referees call the penalties, like hooking, spearing, boarding...
for these penalties a player must leave the ice for 2 minutes. his team will then play "shorthanded," as in 5 against 4. he can return when the other team scores, or his 2 minutes are up, which ever is first.
sometimes there is a more serious penalty, called a major penalty, for which he will have to leave for 5 minutes. and he can not return until the 5 minutes are over, even if the other team scores.
the linesman call the line infractions, like offsides, icing, 2-line passes
for this, the play is just whistled dead and there is a faceoff
the referee's crease is usually where the refs go when they want to talk to each other or a player, and it is where he tells the off ice official what the penalty being called is. he can also go there to ask an off ice official for an instant review, usually on if the puck crossed the goal line or not