Canon PowerShot S3 IS vs Canon PowerShot SD630 digital camera reviews
LCD screen size on Canon PowerShot SD630 is larger, 3" comparing to 2" at Canon PowerShot S3 IS.
These cameras have 6Mpix. This is amount of pixels on each picture (the higher, the better). Picture with large amount of pixels have in general more details.
Canon PowerShot S3 IS has optical zoom 12x. Canon PowerShot SD630 has poorer optical zoom of 3x.