One other important thing about Jack is that on some level he understands the fear that is within the boys. Ralph thinks that having rules and meetings and structure will help the boys deal with their fear of the unknown. This and the sort of coolness the boys sense in him leads them to vote for him. Jack's first impression was one of the angry, dominant leader and the boys were at first putt off by it.
But Jack sees that the hunt and the kill and the celebration of it is something that the boys need, he understands that it allows them to externalize the fear of "the beast." He uses this fear to justify his actions and to compel the boys to follow his orders.
Ralph lacks this understanding and just keeps chasing the dream of being rescued even when the brief period of cohesion around a goal quickly begins to unravel in the face of the nameless, shifting fear of "the beast." His idea of a democratic, rule-based structure cannot survive in the face of that fear.
Ralph prefers to lead in a way that mimics how grownups would behave. He hopes that this will give the "young'uns" a sense of security and would maximize their changes of being rescued. His three priorities are a signal fire, hunting, and shelter. He was elected democratically, and if he has any leadership flaws it would be his tendency to give his followers too much choice.
Jack leads by force and reward. He bullies and bribes people into following him. Typically everyone succumbs to one or the other. He creates a more primal, barbaric sort of sociey in which the boys paint their faces and dance around the fire. Fun and meat are priority, not a signal fire. One gets the impression that Jack may not even want to be rescued.