Balance Board has limited play, meaning its games are designed around standing and moving around on/off the board and every game takes those limitations into account.
Kinect has limited play, (so far) its games are designed for standing and moving around within its view and every game takes those limitations into account.
Balance board action/type games are almost the same ideas as various Kinect games demonstrated. Only game that was obviously different and unattainable from a balance board/wii mote perspective was Kinectimals.
Everythign else could be a balance board/wiimote game or already is in a very similar form.
Obviously the variant portion of the Kinect is the camera system as allows it more functionality with the contrals and visual interactivity, but once you add a wiimote those differences are a lot smaller.
Hell, with a Wiimote and balance board you could actually play Forza sitting down. ;) The real game not some side demo stearing only thing.
