Sigma SD1 Merrill has a
15.0MP APS-C (24 x 16 mm ) sized CMOS (Foveon X3) sensor and features Dual True II processor. On the other hand, Panasonic G85 has a
16.0MP Four Thirds (17.3 x 13 mm ) sized CMOS sensor .
Another similarity between these two cameras is that both Panasonic G85 and Sigma SD1 Merrill 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 SD1 Merrill and G85 sensor size comparison.
As seen above, Sigma SD1 Merrill 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.