Both Panasonic ZS7 and Nikon P330 have 12.0 MP resolution sensors but Panasonic ZS7's sensor is 1/2.3-inch (6.08 x 4.56 mm ) and Nikon P330's sensor is 1/1.7-inch (7.44 x 5.58 mm ).
Since Nikon P330'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 Panasonic ZS7.
Below you can see the ZS7 and P330 sensor size comparison.
As seen above, Nikon P330 has a 1.5x Larger sensor area than Panasonic ZS7. 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.