Leica SL2 has a
47.0MP Full frame (36 x 24 mm ) sized CMOS sensor and features Maestro III processor. On the other hand, Hasselblad X1D has a
51.0MP Medium format (44 x 33 mm ) sized CMOS sensor .
Another difference between these two cameras is that Leica SL2'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 SL2 and X1D sensor size comparison.
As seen above, Hasselblad X1D has a 1.7x Larger sensor area than Leica SL2. 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.