Both Fujifilm XP90 and Casio EX-ZR800 have 16.0 MP resolution sensors but Fujifilm XP90's sensor is 1/2.3 (6.17 x 4.55 mm ) and Casio EX-ZR800's sensor is 1/2.3-inch (6.17 x 4.55 mm ).
Since Casio EX-ZR800'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 Fujifilm XP90.
Below you can see the XP90 and EX-ZR800 sensor size comparison.
Fujifilm XP90 and Casio EX-ZR800 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.