Both Ricoh GR II and Panasonic ZS35 have 16.0 MP resolution sensors but Ricoh GR II's sensor is APS-C (23.7 x 15.7 mm ) and Panasonic ZS35's sensor is 1/2.3-inch (6.08 x 4.56 mm ).
Since Ricoh GR II'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 Panasonic ZS35.
Below you can see the GR II and ZS35 sensor size comparison.
As seen above, Ricoh GR II has a 13.4x Larger sensor area than Panasonic ZS35. 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.