Both Nikon B500 and Sony W650 have 16.0 MP resolution sensors but Nikon B500's sensor is 1/2.3 (6.17 x 4.55 mm ) and Sony W650's sensor is 1/2.3-inch (6.17 x 4.55 mm ).
Since Sony W650'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 Nikon B500.
Below you can see the B500 and W650 sensor size comparison.
Nikon B500 and Sony W650 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.