Both Nikon D7000 and Casio EX-H30 have 16.0 MP resolution sensors but Nikon D7000's sensor is APS-C (23.6 x 15.7 mm ) and Casio EX-H30's sensor is 1/2.3-inch (6.17 x 4.55 mm ).
Since Nikon D7000'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-H30.
Below you can see the D7000 and EX-H30 sensor size comparison.
As seen above, Nikon D7000 has a 13.2x Larger sensor area than Casio EX-H30. 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.