But how different? This is not perfect, but here is a GIF that shows just how the controller has apparently changed between summer 2011 and this spring. The photo showed a new square button on the left side and shifted start and select buttons. More importantly, the image depicted true analog joysticks.
Granted, Nintendo has yet to confirm the recently leaked photo. But still, have a look and compare for yourself.
This image popped up on Japanese bulletin boards, but I believe it was created on Western forums. If you know the proper source, please let Kotaku know.