Islebound: Emerald Edition is a special edition of the game with some altered components and rules. It's best to think of it as a variant of the game, rather than a 2nd edition. This edition removes the book resource from the original game and replaces it with emeralds. Emeralds have different uses than books. You collect them when visiting a player-owned town and when you taking over a town. Emeralds must be used to buy building cards, and they can also be used to perform special abilities, such as keeping pirates and serpents after combat!
It's tempting to think that to win this game, you have to join the collective, but really you're just exposing how well you can clone your friends. This of course includes knowing if THEY would answer how they think YOU would answer. Tricky stuff.