Not sure about what you're trying to ask, as you clearly make/save worlds and characters separately..

You first have a character list, with all your made characters.
Then after picking one you come to the world list..
Where you can enter any of your worlds starting it in singleplayer/multiplayer style,
or just switch tab and look for/join others worlds.

You can even move anything you can carry between worlds because of this.



Anyways, if none of this helped with what you were wondering, please try explain what it is you're asking for again. =)