Olympus SZ-30MR has a 16.0MP 1/2.3-inch (6.17 x 4.55 mm ) sized CMOS sensor and features TruePic III+ processor. On the other hand, Nikon D800 has a 36.0MP Full frame (35.9 x 24 mm ) sized CMOS sensor and features Expeed 3 processor.
Nikon D800's sensor provides 20MP more than Olympus SZ-30MR'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 SZ-30MR and D800 sensor size comparison.
![Olympus SZ-30MR vs Nikon D800 Sensor Size Comparison]()
Sensor Size and Resolution Comparison image of Olympus SZ-30MR and Nikon D800 Cameras
As seen above, Nikon D800 has a 30.7x Larger sensor area than Olympus SZ-30MR. 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.