Throughout the play he is deliberating, pondering and worrying.
Hamlet, after learning that his father's death was a murder an But Laertes ignored that advice. There is no soul-searching, no worrying about an afterlife and no concerns about conscience.
He does not lead an army or even a mob. He receives a visit from the ghost of his father which urges him to "revenge [Claudius'] foul and most unnatural murder" I, v, 32 of Old Hamlet.
Hamlet wasn't naturally vengeful, but he was loyal to his father so he swore an oath to his father to seek revenge. Even though he is not King of Norway, he is actively doing everything he can to revenge his father and to gain back the land that was lost to Denmark.
Also please see the following very short essays about Fortinbras and Hamlet:. It is a simple matter. Had Laertes acted upon the honorable promptings of his conscience, he would have avoided his own eath and, by allying himself with Hamlet, would have won the gratitude of the future King.
Not sure that the ghost was really his father rather than a deceitful demon, he staged the Mousetrap to verify Claudius' guilt.
Claudius must die, die, die. Leartes chases after false honor and is not able to detect something really worth fighting for.