Nikon S100 has a
16.0MP 1/2.3-inch (6.17 x 4.55 mm ) sized CMOS sensor and features Expeed C2 processor. On the other hand, Nikon S80 has a
14.0MP 1/2.3-inch (6.17 x 4.55 mm ) sized CCD sensor and features Expeed C2 processor.
Below you can see the S100 and S80 sensor size comparison.
Nikon S100 and Nikon S80 have the same sensor sizes so they will provide same level of control over the depth of field when used with same focal length and aperture. On the other hand, since Nikon S80 has 14% larger pixel area (2.01µm2 vs 1.76µm2) compared to Nikon S100, it has larger pixel area to collect light hence potential to have less noise in low light / High ISO images.