Samsung NX mini has a
20.5MP 1' (13.2 x 8.8 mm ) sized BSI-CMOS sensor . On the other hand, Hasselblad X1D II 50C has a
51.0MP Medium format (44 x 33 mm ) sized CMOS sensor .
Hasselblad X1D II 50C's sensor provides 30.5MP more than Samsung NX mini'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.
Below you can see the NX mini and X1D II 50C sensor size comparison.
As seen above, Hasselblad X1D II 50C has a 12.5x Larger sensor area than Samsung NX mini. 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.