Both Ricoh WG-M1 and Olympus TG-610 have 14.0 MP resolution sensors but Ricoh WG-M1's sensor is 1/2.3" (6.17 x 4.55 mm ) and Olympus TG-610's sensor is 1/2.3-inch (6.17 x 4.55 mm ).
Since Olympus TG-610'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-M1.
Below you can see the WG-M1 and TG-610 sensor size comparison.
Ricoh WG-M1 and Olympus TG-610 have the same sensor sizes so they will provide same level of control over the depth of field when used with same focal length and aperture.