What are the differences between the books The Coral Island by R. M. Ballantyne and Lord of the Flies by William Golding?

In the Coral Island Jack, Ralph and Peterkin gradually evolve from a state which they see as being primative castaways. They build a shelter, make weapons, explore, harvest fruit and hunt pigs, fish and wild fowl. In Lord of the Flies a group of "civilised" schoolboys start off with good intentions but their society gradually falls apart and they revert to a state of primative savagery.