New figurines not only give you new characters, but full worlds.
http://www.nintendoworldreport.com/news/32994
Disney Infinity will feature multiple game worlds that are character specific. This information was revealed at today's Disney Infinity event.
Disney Infinity will come with three figurines to start: Sulley from Monsters Inc., Mr. Incredible from The Incredibles, and Capt. Jack Sparrow from Pirates of the Caribbean. These characters are brought to life in game through a reader which features three different slots. Two of these slots are for playable characters, one of which is for power discs. Power discs act as power-ups for the many characters.
When the characters are in game they can either go to a specific world meant only for them, or a Toy Box mode, where any of the characters can meet up.
The Toy Box mode features both goals as well as free-play options. You can solve puzzles using the toys you have accumulated as well as build structures using hundreds of different pieces.