Both Olympus TG-6 and Sony S2100 have 12.0 MP resolution sensors but Olympus TG-6's sensor is (1/2. ) and Sony S2100's sensor is 1/2.3-inch (6.17 x 4.55 mm ).
Since Sony S2100'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 Olympus TG-6.
Below you can see the TG-6 and S2100 sensor size comparison.
As seen above, Sony S2100 has a 0.0x Larger sensor area than Olympus TG-6. 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.