Nikon D80 has a 10.0MP APS-C (23.6 x 15.8 mm ) sized CCD sensor . On the other hand, Ricoh GXR A16 24-85mm F3.5-5.5 has a 16.0MP APS-C (23.6 x 15.7 mm ) sized CMOS sensor and features Smooth Imaging Engine IV processor.
Ricoh GXR A16 24-85mm F3.5-5.5's sensor provides 6MP more than Nikon D80'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 D80 and GXR A16 24-85mm F3.5-5.5 sensor size comparison.
Nikon D80 and Ricoh GXR A16 24-85mm F3.5-5.5 have almost the same sensor size so none of them has any significant advantage over other in providing control over depth of field when used with same focal length and aperture.