Both Ricoh WG-50 and Olympus SH-3 have 16.0 MP resolution sensors but Ricoh WG-50's sensor is (1/2. ) and Olympus SH-3's sensor is 1/2.3' (6.17 x 4.55 mm ).
Since Olympus SH-3'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 Ricoh WG-50.
Below you can see the WG-50 and SH-3 sensor size comparison.
As seen above, Olympus SH-3 has a infx Larger sensor area than Ricoh WG-50. 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.