Both FujiFilm F70EXR and Nikon P7100 have 10.0 MP resolution sensors but FujiFilm F70EXR's sensor is 1/2-inch (6.4 x 4.8 mm ) and Nikon P7100's sensor is 1/1.7-inch (7.44 x 5.58 mm ).
Since Nikon P7100'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 F70EXR.
Below you can see the F70EXR and P7100 sensor size comparison.
As seen above, Nikon P7100 has a 1.4x Larger sensor area than FujiFilm F70EXR. 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.