Ricoh G900 has a
20.0MP (1/2. ) sized BSI-CMOS sensor . On the other hand, Olympus SZ-31MR iHS has a
16.0MP 1/2.3-inch (6.17 x 4.55 mm ) sized BSI-CMOS sensor and features Dual TruePic V processor.
Below you can see the G900 and SZ-31MR iHS sensor size comparison.
As seen above, Olympus SZ-31MR iHS has a infx Larger sensor area than Ricoh G900. 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.