These quests can be with or without an elite dragon on it. There are quests that are easy and can be done solo. The time point a quest available is dependent on the difficulty to be completed and they are divided (black, blue, purple).
World quests are divided in difficulty to be completed. When you hit max level you will find all the world quests when opening your map. You can choose what you want to do, which zone(s) you want to go to. Every time you log in, your map is filled with various objectives, various types of gameplay with varied reasons and awards. World quests will be ongoing constantly, and constantly shuffling. Since the Broken Isles is flexible (mob levels scales to your lvl were ever you are in Broken Isles) endgame will be all around the Broken Isles. We will have awesome lore and instead of sending followers out on missions, we will go out in the world (Broken Isles) ourselves! In Legion, we will have a mix between them.
In Mist of Pandaria we had awesome lore questing. In Warlords of Draenor we have our Garrison with followers that we send out on missions. In Legion, when hitting max level (110) you will discover a new type of end gaming.