Ralph and Jack of Lord of the Flies represent two differing allegorical types: Ralph is the charismatic leader: golden-haired, athletic of body; Jack is the fiery, forceful and dominating ruler: red-haired, loud, forceful, brutal. He is also an exigent leader, concentrating on the demands of the moment and what is most engaging for his followers. The hunt is a physical and emotional activity that will bring those he leads together; it will satisfy their basic need to eat as well as affording him command.
On the other hand, Ralph is more conscious of the long-range needs of the boys, encouraging them to build the shelters and to maintain the rescue fire. Ralph considers these needs before those of his own for dominance, while Jack selfishly wants his place as leader before other considerations. Ralph is a more cerebral leader whereas Jack dominatation is in the realm of the physical.
In Lord of the Flies, Ralph and Jack both represent opposing modes of experience and feeling. Ralph believes that the boys' main goal should be surviving for long enough to get rescued from the island. This is why he puts emphasis on building and maintaining shelters and keeping the signal fire going. Jack, on the other hand, believes that the boys have little chance of getting rescued and that they should focus on developing an existence on the island. This is why he gathers a group of boys together to begin hunting for meat and neglects the signal fire. Ralph's feelings still revolve around the importance of civilization, so the decisions that he makes reflect this belief; Jack's feelings revolve around becoming one with the island, so his decisions are based on this belief. The two boys cannot communicate because their beliefs and feelings totally clash and one will not bend to try to support or understand the other.