Hi PhroZenOne,
i have thought a little bit about it and i think, i can answer the question 
Map: Can be a Level or a World
Level: Can be a world, if no other levels will be added, but generally it is a part of a world
World: A collection of levels that are connected to each other. If you use streaming you will put different levels together.
At least it can be confusing cause all these 3 things are very similar to each other.
Hope that helps