Both Canon 5DS R and Hasselblad X1D have 51.0 MP resolution sensors but Canon 5DS R's sensor is Full frame (36 x 24 mm ) and Hasselblad X1D's sensor is Medium format (44 x 33 mm ).
Since Hasselblad X1D'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 Canon 5DS R.
Another difference between these two cameras is that Canon 5DS R'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 moire occurring in certain scenes.
Below you can see the 5DS R and X1D sensor size comparison.
As seen above, Hasselblad X1D has a 1.7x Larger sensor area than Canon 5DS R. 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.