Both Panasonic ZS70 and Canon G7 X MIII have 20.0 MP resolution sensors but Panasonic ZS70's sensor is (1/2. ) and Canon G7 X MIII's sensor is 1″ (13.2 x 8.8 mm ).
Since Canon G7 X MIII'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 ZS70.
Below you can see the ZS70 and G7 X MIII sensor size comparison.
As seen above, Canon G7 X MIII has a infx Larger sensor area than Panasonic ZS70. 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.