Panasonic ZS1 has a
10.0MP 1/2.5-inch (5.744 x 4.308 mm ) sized CCD sensor . On the other hand, Sony S2100 has a
12.0MP 1/2.3-inch (6.17 x 4.55 mm ) sized CCD sensor and features Bionz processor.
Below you can see the ZS1 and S2100 sensor size comparison.
As seen above, Sony S2100 has a 1.1x Larger sensor area than Panasonic ZS1. 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.