Both Ricoh WG-50 and Fujifilm F660EXR have 16.0 MP resolution sensors but Ricoh WG-50's sensor is (1/2. ) and Fujifilm F660EXR's sensor is 1/2-inch (6.4 x 4.8 mm ).
Since Fujifilm F660EXR'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 F660EXR sensor size comparison.
As seen above, Fujifilm F660EXR 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.