The game has three most general types of quests:
1) Story quests advance the story line leading the players through exciting new places, mysterious wonders and marvelous islands. Such quests have red background and holiday framing on their icon in the quest line.
2) Building quests grant access to different structures and profitable buildings giving your islands diverse looks and production resources. The icons of these quests are dark blue and have simple framing.
3) Side quests contain various tasks concerning all the resources and buildings you've acquired so far. They are not crucial for advancing in the story line and only supply it with additional details. These quests are marked with standard background and framing of the icon.