Both Ricoh WG-70 and Nikon AW120 have 16.0 MP resolution sensors but Ricoh WG-70's sensor is (1/2. ) and Nikon AW120's sensor is 1/2.3-inch (6.17 x 4.55 mm ).
Since Nikon AW120'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 AW120 sensor size comparison.
As seen above, Nikon AW120 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.