Both Sony WX500 and Panasonic FZ80 have 18.0 MP resolution sensors but Sony WX500's sensor is 1/2.3 (6.17 x 4.55 mm ) and Panasonic FZ80's sensor is (1/2. ).
Since Sony WX500'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 FZ80.
Below you can see the WX500 and FZ80 sensor size comparison.
As seen above, Sony WX500 has a infx Larger sensor area than Panasonic FZ80. 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.