Though Jack has proven experience at being a leader, Ralph is the one the boys choose to be their leader, despite his lack of demonstrable leadership skills. He blew the conch, so the little boys see him as leader. Ralph graciously allows Jack to be in charge of the hunters, so Jack is appeased.
Neither Ralph nor Jack cares for Piggy in the beginning, though Ralph is certainly more tolerant of him than Jack. Jack's hatred of Piggy only increases as the novel progresses and ends in Piggy's murder. Ralph, on the other hand, comes to appreciate Piggy's wisdom and at the end of the novel, and he is the only one left standing with Piggy. When the naval officer arrives to rescue them, Ralph weeps for "the fall through the air of the true, wise friend called Piggy."
While Ralph consistently tries to maintain order and civilized behavior, Jack is consumed by hunting and meat. While Ralph selflessly works on shelters for all, Jack hunts on his own because he is obsessed with killing a pig. When things begin to fall apart, Ralph grows wiser but Jack grows stronger. Ralph wants to talk and be reasonable, but Jack only wants to use violence and force to maintain his power as chief over a tribe of "savages."
There are moments in the novel when Ralph and Jack are united, such as when they are exploring the island or during the only pig hunt Ralph ever participates in, but they are usually depicted as unable to communicate:
They walked along, two continents of experience and feeling, unable to communicate.
In the end, it is Ralph's consistent desire to do the right things, even when it is unbearably hard and he has to fight