iSight vs Facetime HD (Macbook vs Macbook Pro) While checking the tech specs I see iSight on Mac book and FaceTime HD on Mac book pro.

I tried finding solution myself through google and sources but found no justifiable response.
Can some one tell me the difference ?
The only official specifications I can find on the FaceTime HD camera is that they send 720p HD signal whereas the iSight cameras recorded 640x480.