Panasonic ZS1 has a 10.0MP 1/2.5-inch (5.744 x 4.308 mm ) sized CCD sensor . On the other hand, Leica C has a 12.0MP 1/1.7-inch (7.44 x 5.58 mm ) sized CMOS sensor .
Below you can see the ZS1 and C sensor size comparison.
As seen above, Leica C has a 1.7x 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.