Both Nikon S6500 and Olympus SH-2 have 16.0 MP resolution sensors but Nikon S6500's sensor is 1/2.3-inch (6.17 x 4.55 mm ) and Olympus SH-2's sensor is 1/2.3' (6.17 x 4.55 mm ).
Since Olympus SH-2's has a larger sensor area with the same resolution, this means that it also has a larger pixel area hence better light collecting capacity for a given aperture compared to Nikon S6500.
Below you can see the S6500 and SH-2 sensor size comparison.
Nikon S6500 and Olympus SH-2 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.