Both Samsung SL30 and Nikon P7000 have 10.0 MP resolution sensors but Samsung SL30's sensor is 1/2.3-inch (6.08 x 4.56 mm ) and Nikon P7000's sensor is 1/1.7-inch (7.44 x 5.58 mm ).
Since Nikon P7000'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 Samsung SL30.
Below you can see the SL30 and P7000 sensor size comparison.
As seen above, Nikon P7000 has a 1.5x Larger sensor area than Samsung SL30. 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.