Both Canon G7 X MII and Panasonic GX8 have 20.0 MP resolution sensors but Canon G7 X MII's sensor is 1" (13.2 x 8.8 mm ) and Panasonic GX8's sensor is Four Thirds (17.3 x 13 mm ).
Since Panasonic GX8'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 G7 X MII.
Below you can see the G7 X MII and GX8 sensor size comparison.
As seen above, Panasonic GX8 has a 1.9x Larger sensor area than Canon G7 X MII. 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.