Fujifilm X100 has a 12.0MP APS-C (23.6 x 15.8 mm ) sized CMOS sensor and features EXR processor. 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.
Another difference between these two cameras is that Fujifilm X100's sensor lacks anti-alias (Low-Pass) filter. Removing anti-alias filter increases the sharpness and level of detail but at the same time, it increases the chance of moire occurring in certain scenes.
Below you can see the X100 and GXR A16 24-85mm F3.5-5.5 sensor size comparison.
Fujifilm X100 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.