Nikon S6100 has a
16.0MP 1/2.3-inch (6.17 x 4.55 mm ) sized CCD sensor and features Expeed C2 processor. On the other hand, Olympus TG-320 has a
14.0MP 1/2.3-inch (6.17 x 4.55 mm ) sized CCD sensor and features TruePic III+ processor.
Below you can see the S6100 and TG-320 sensor size comparison.
Nikon S6100 and Olympus TG-320 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 Olympus TG-320 has 15% larger pixel area (2.04µm2 vs 1.76µm2) compared to Nikon S6100, it has larger pixel area to collect light hence potential to have less noise in low light / High ISO images.