Both Ricoh WG-30W and Sony NEX-5T have 16.0 MP resolution sensors but Ricoh WG-30W's sensor is 1/2.3 (6.17 x 4.55 mm ) and Sony NEX-5T's sensor is APS-C (23.4 x 15.6 mm ).
Since Sony NEX-5T'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-30W.
Below you can see the WG-30W and NEX-5T sensor size comparison.
As seen above, Sony NEX-5T has a 13.0x Larger sensor area than Ricoh WG-30W. 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.