Both Nikon D7000 and Canon SX530 HS have 16.0 MP resolution sensors but Nikon D7000's sensor is APS-C (23.6 x 15.7 mm ) and Canon SX530 HS's sensor is 1/2.3' (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 Canon SX530 HS.
Below you can see the D7000 and SX530 HS sensor size comparison.
As seen above, Nikon D7000 has a 13.2x Larger sensor area than Canon SX530 HS. 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.