Both Ricoh WG-6 and YI M1 have 20.0 MP resolution sensors but Ricoh WG-6's sensor is 1/2.3-inch (6.17 x 4.55 mm ) and YI M1's sensor is Four Thirds (17.3 x 13 mm ).
Since YI M1'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-6.
Below you can see the WG-6 and M1 sensor size comparison.
As seen above, YI M1 has a 8.0x Larger sensor area than Ricoh WG-6. 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.