Canon 5D MIII has a
22.0MP Full frame (36 x 24 mm ) sized CMOS sensor and features Digic 5+ processor. On the other hand, FujiFilm JZ500 has a
14.0MP 1/2.3-inch (6.17 x 4.55 mm ) sized CCD sensor .
Canon 5D MIII's sensor provides 8MP more than FujiFilm JZ500'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 5D MIII and JZ500 sensor size comparison.
As seen above, Canon 5D MIII has a 30.8x Larger sensor area than FujiFilm JZ500. 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.