Sigma Quattro H has a 45.0MP APS-H
(26.6 x 17.9 mm ) sized CMOS (Foveon X3) sensor and features Dual TRUE III processor. On the other hand, Sony A7CR has a 61.0MP Full frame
(35.8 x 23.8 mm ) sized BSI-CMOS sensor and features Bionz XR processor.
Sony A7CR's sensor provides 16MP more than Sigma Quattro H's sensor, which gives a significant advantage in real life. You can print your images larger or crop more freely.
On the other hand, please keep in mind that Max sensor resolution is not the only determinant of resolving power. Factors such as the optical elements, low pass filter, pixel size and sensor technology also affects the final resolution of the captured image.
Another similarity between these two cameras is that both Sony A7CR and Sigma Quattro H 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 Quattro H and A7CR sensor size comparison.
As seen above, Sony A7CR has a 1.8x Larger sensor area than Sigma Quattro H. 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.