Panasonic G5 has a 16.0MP Four Thirds (17.3 x 13 mm ) sized CMOS sensor and features Venus Engine VII FHD processor. On the other hand, Samsung NX mini has a 20.5MP 1" (13.2 x 8.8 mm ) sized BSI-CMOS sensor . Samsung NX mini's sensor provides 4.5MP more than Panasonic G5'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 G5 and NX mini sensor size comparison.
As seen above, Panasonic G5 has a 1.9x 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.