Nikon D5 has a 21.0MP Full frame (35.8 x 23.9 mm ) sized CMOS sensor and features Expeed 5 processor. On the other hand, Samsung ST100 has a 14.0MP 1/2.3" (6.17 x 4.55 mm ) sized CCD sensor . Nikon D5's sensor provides 7MP more than Samsung ST100'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 D5 and ST100 sensor size comparison.
As seen above, Nikon D5 has a 30.5x Larger sensor area than Samsung ST100. 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.