Ricoh WG-4 has a
16.0MP 1/2.3-inch (6.17 x 4.55 mm ) sized BSI-CMOS sensor . On the other hand, Olympus TG-310 has a
14.0MP 1/2.3-inch (6.17 x 4.55 mm ) sized CCD sensor and features TruePic III+ processor.
Below you can see the WG-4 and TG-310 sensor size comparison.
Ricoh WG-4 and Olympus TG-310 have the same sensor sizes so they will provide same level of control over the depth of field when used with same focal length and aperture. On the other hand, since Olympus TG-310 has 15% larger pixel area (2.04µm2 vs 1.76µm2) compared to Ricoh WG-4, it has larger pixel area to collect light hence potential to have less noise in low light / High ISO images.