Both Panasonic G85 and Nikon L31 have 16.0 MP resolution sensors but Panasonic G85's sensor is Four Thirds (17.3 x 13 mm ) and Nikon L31's sensor is 1/2.3-inch (6.17 x 4.55 mm ).
Since Panasonic G85'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 Nikon L31.
Another difference between these two cameras is that Panasonic G85's sensor lacks anti-alias (Low-Pass) filter. Removing anti-alias filter increases the sharpness and level of detail but at the same time, it increases the chance of moire occurring in certain scenes.
Below you can see the G85 and L31 sensor size comparison.
As seen above, Panasonic G85 has a 8.0x Larger sensor area than Nikon L31. 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.