Nikon Z30 has a
21.0MP APS-C (23.5 x 15.7 mm ) sized CMOS sensor and features Expeed 6 processor. On the other hand, Canon M50 II has a
24.0MP APS-C (22.3 x 14.9 mm ) sized CMOS sensor and features Digic 8 processor.
Another difference between these two cameras is that Nikon Z30's sensor lacks anti-alias (Low-Pass) filter. 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 Z30 and M50 Mark II sensor size comparison.
As seen above, Nikon Z30 has a 1.1x Larger sensor area than Canon M50 II. 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.