Nikon S8200 has a
16.0MP 1/2.3-inch (6.17 x 4.55 mm ) sized BSI-CMOS sensor and features Expeed C2 processor. On the other hand, Panasonic ZS20 has a
14.0MP 1/2.3-inch (6.08 x 4.56 mm ) sized CMOS sensor .
Below you can see the S8200 and ZS20 sensor size comparison.
Nikon S8200 and Panasonic ZS20 have almost the same sensor size, so neither of them has any significant advantage over the other in terms of providing control over depth of field when used with the same focal length and aperture.