Both Nikon D7000 and Fujifilm S8400W have 16.0 MP resolution sensors but Nikon D7000's sensor is APS-C (23.6 x 15.7 mm ) and Fujifilm S8400W'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 Fujifilm S8400W.
Below you can see the D7000 and S8400W sensor size comparison.
As seen above, Nikon D7000 has a 13.2x Larger sensor area than Fujifilm S8400W. 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.