Ralph is elected chief on the island even though Piggy is the most intelligent of the boys and Jack is "the most obvious leader." Ralph's first decision as chief is to share power; he allows Jack to be "in charge of the choir" and to choose what duty they will perform. Thus Ralph is non-dictatorial from the beginning. During the second meeting when the boys run away to build a fire, leaving Ralph and Piggy behind, Ralph runs after them, following the will of the people. Ralph establishes rules for the good of the society, not to promote himself, and he pitches in to build the shelters himself rather than just giving orders. He enforces the rule of the conch at meetings, allowing everyone to have a chance to speak. When they go in search of the beast, he doesn't order others into danger; instead, he volunteers to go first. He reminds the boys they have voted him chief, but when the evening meeting deteriorates and the boys run down to the beach in a "random scatter," he refuses to blow the conch, not willing to impose order on the group by sheer command. He listens to others' opinions, including Piggy and Samneric.
Jack, on the other hand, is an autocrat. He believes he should be chief based solely on the fact that he is choir leader and "can sing C sharp." This is similar to the divine right of kings. Although he agrees to the rules at first, when others disagree with him, he wants to squelch their free speech rights. He says, "We don't need the conch anymore. ... It's time some people knew they've got to keep quiet and leave deciding things to the rest of us." He suggests an oligarchy where only those in power make the decisions.
When Jack leaves Ralph's group and draws boys away to his tribe, he creates a regime that brings honor to himself rather than benefiting the group. He has two boys punctuate his declaration by saying, "The chief has spoken." At his feast, he sets himself up as the central figure, sitting garlanded "like an idol." He beats Wilfred for no apparent reason other than to show his power over the boys. He uses theft, violence, and terror to maintain control, and his boys have no real say in their governance. Samneric tell Ralph that Jack is a "terror." Jack usurps so much control over the boys that he gets them to hunt another human being.
Jack represents an autocratic form of government that puts the desires of the leader above the needs of the group, while Ralph seeks to institute a democratic society.
The differences between the two boy leaders in Lord of the Flies are pretty distinctive. Ralph is the first to suggest that the boys elect a chief to lead the group and preserve order. He establishes the conch as a democratic symbol of free speech, and he attempts to organize the boys and assign responsibilities. He recognizes Piggy's intelligence and utilizes his knowledge. Jack, on the other hand, believes that he should be chief because he is the head of the choir; he does not favor a vote to name the leader. Even before Ralph is elected, Jack snaps orders at his group. Jack shuns the power of the conch, hates Piggy because of his weight and brains, neglects the young'uns because of their age and physical weaknesses, and eventually takes control through violence and the threat of death. His power-hungry yearnings finally lead to torture and murder.