Laertes wants revenge, he is not concerned with punishment. Laertes is concerned with the physical and the present, "That both the worlds I give to negligence,"(Act4, 5:134) he declares. Hamlet however, philosophises about the afterlife, and whether "...in that sleep of death what dreams may come."(Act 3, 1:66)
Hamlet and Laertes represent the two extremities of the act of revenge: perpetual contemplation over circumstances leading to procrastination; and acting on impulsion and without reasoning. Revenge was the driving force behind these character's actions and this led to their eventual downfall.
Fortinbras is the son of Old Fortinbras, King of Norway, slain during battle by King Hamlet. Through a "seal'd compact,"(Act 1, 1:89) the lands of Old Fortinbras are forfeited to Denmark. As a mark of honour as was the style, Fortinbras vows to avenge his father's death and reclaim the territory lost. Fortinbras tends not to be active in the play, more often, he is spoken of. Fortinbras is the converse of character to Hamlet: the scholar and the soldier, the man of procrastination and the man of reason and action.
When Fortinbras' forces pass through Denmark, Hamlet chances to speak with one of the soldiers of the Norwegian army. Hamlet compares himself to Fortinbras, "...How stand I then?"(Act 4, 4: 56) and reproaches himself