Both Casio EX-Z450 and FujiFilm Z700EXR have 12.0 MP resolution sensors but Casio EX-Z450's sensor is 1/2.3-inch (6.17 x 4.55 mm ) and FujiFilm Z700EXR's sensor is 1/2-inch (6.4 x 4.8 mm ).
Since FujiFilm Z700EXR'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 Casio EX-Z450.
Below you can see the EX-Z450 and Z700EXR sensor size comparison.
Casio EX-Z450 and FujiFilm Z700EXR have almost the same sensor size, so neither of them has any significant advantage over the other in terms of providing control over depth of field when used with the same focal length and aperture.