Both Olympus TG-3 and Panasonic TS6 have 16.0 MP resolution sensors but Olympus TG-3's sensor is (1/2. ) and Panasonic TS6's sensor is 1/2.33' (6.08 x 4.56 mm ).
Since Panasonic TS6'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-3.
Below you can see the TG-3 and TS6 sensor size comparison.
As seen above, Panasonic TS6 has a infx Larger sensor area than Olympus TG-3. 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.