Jack's use of power is ambitious and self-serving. When Ralph was chief, he used the role to help the tribe and built huts for the littluns and oversaw the building of a signal fire; Jack, on the other hand, acts completely different. He shows off his power to Piggy and Ralph at the feast by making one of the littluns serve him:
"Give me a drink."
Henry brought him a shell and he drank, watching Piggy and Ralph over the jagged rim. Power lay in the brown swell of his forearms: authority sat on his shoulder and chattered in his ear like an ape." (Chapter 9)
Unlike Ralph, he has seized power for himself, taken control of the tribe through sheer force. Instead of seeing being chief as a 'service' role, he expects and demands to be served by the other boys. He wants to be exalted and recognized.
In Lord of the Flies, there are many contradictory and conflicting emotions facing this group of school boys who find themselves on an island with no guidance from any adults in their attempts to survive and to ensure their collective safety. In assigning power within the group, Piggy and Ralph recognize the need to form a cohesive group so that they can be effective in building shelters, finding food, keeping the rescue fire going and setting up a secure community where everyone will be safe. On the other hand, Jack sees great potential for his own self-development through a misuse of power. His grounds for being chief are based on what he considers to be his proven track-record as he is "chapter chorister and head boy." He does not assess the situation as Ralph has done with Piggy's help and his faith in his personal attributes and ability to "sing C sharp" indicate that he has no appreciation for the predicament and no planning ability. The conch sets Ralph apart but Jack's self-assurance gives him power.
Ralph takes his appointment as chief seriously and allocates jobs appropriately whereas Jack acts in the moment with little concern for consequences. One of the biggest differences between Ralph's democratic style of leadership and Jack's leadership is in their use or abuse of their seniority. Even though Jack was not voted chief he does hold a position of authority, especially over the choir boys. Ralph's recognition of this speaks to his ability to work as a team rather than as a figurehead. Unfortunately, Ralph has overlooked Jack's competitive nature and controlling personality.
Jack sees himself as an expert in all things related to hunting, making himself invincible with his face paint and thinking that an apology is sufficient to obviate his flagrant abuse of power when he lets the fire go out. He sees others as followers who must obey him. He does not appreciate interference, especially from Piggy and uses the boys' fear against them in establishing himself. He attempts to make the boys so reliant on him that they cannot function without him and if they do, he wants then to understand that they are surely doomed. The beast can only be controlled if Jack takes charge. He uses this power consistently, from the time that he denies the existence of a beast to leaving a "gift' for it. He challenges the beast and sets his tribe up as hunters and even suggests that he has the power to include or exclude the other boys from joining the feast. Ultimately, he will withdraw from his apparent position of power when the naval officer asks Ralph who the "boss' is. For the first time, Jack reveals that he is aware of his unacceptable behavior in the eyes of the civilized world, hesitating and making the decision not to reveal himself as leader, letting Ralph face any potential consequences. Jack has always hid his cowardice behind his seemingly powerful facade.