In MapleStory, a world is a set of servers that you connect to. Scania and Windia are examples of worlds. Content in different worlds is always the same, but each world has a different group of players and a distinct economy. Please keep in mind that characters created in a certain world usually cannot be transferred to other worlds, so it’s best to find out what world your friends are playing in before you create your character.
Some worlds are merged into a World Alliance. This means that characters in the merged worlds that belong to the same World Alliance are able to play with each other.
Channels are instances of the MapleStory game. Within each world, there are multiple channels where you can play, so if one channel is too crowded, you can move to a less-populated channel. All channels are exactly the same with the exception of the people playing in them.