Both Ricoh WG-70 and Fujifilm F600 EXR have 16.0 MP resolution sensors but Ricoh WG-70's sensor is (1/2. ) and Fujifilm F600 EXR's sensor is 1/2-inch (6.4 x 4.8 mm ).
Since Fujifilm F600 EXR'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-70.
Below you can see the WG-70 and F600 EXR sensor size comparison.
As seen above, Fujifilm F600 EXR has a infx Larger sensor area than Ricoh WG-70. 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.