Both Fujifilm X100S and Panasonic G85 have 16.0 MP resolution sensors but Fujifilm X100S's sensor is APS-C (23.6 x 15.8 mm ) and Panasonic G85's sensor is Four Thirds (17.3 x 13 mm ).
Since Fujifilm X100S'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 G85.
Another similarity between these two cameras is that both Panasonic G85 and Fujifilm X100S sensors lack anti-alias (Low-Pass) filters. Removing anti-alias filter increases the sharpness and level of detail but at the same time, it increases the chance of moiré occurring in certain scenes.
Below you can see the X100S and G85 sensor size comparison.
As seen above, Fujifilm X100S has a 1.7x Larger sensor area than Panasonic G85. 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.