Sigma SD14 has a
5.0MP APS-C (20.7 x 13.8 mm ) sized CMOS (Foveon X3) sensor . On the other hand, Kodak M320 has a
9.0MP 1/2.5-inch (5.744 x 4.308 mm ) sized CCD sensor .
Another difference between these two cameras is that Sigma SD14's sensor lacks anti-alias (Low-Pass) filter. Removing anti-alias filter increases the sharpness and level of detail but at the same time, it increases the chance of moiré occurring in certain scenes.
Below you can see the SD14 and M320 sensor size comparison.
As seen above, Sigma SD14 has a 11.5x Larger sensor area than Kodak M320. Larger sensors give photographer more control on the depth of field and blurry background compared to smaller sensor when shot in same focal length and aperture.