Both Casio EX-Z550 and Nikon 1 J3 have 14.0 MP resolution sensors but Casio EX-Z550's sensor is 1/2.3" (6.17 x 4.55 mm ) and Nikon 1 J3's sensor is 1" (13.2 x 8.8 mm ).
Since Nikon 1 J3'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-Z550.
Below you can see the EX-Z550 and 1 J3 sensor size comparison.
As seen above, Nikon 1 J3 has a 4.1x Larger sensor area than Casio EX-Z550. 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.