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. On the other hand, Fujifilm S8400W has a
16.0MP 1/2.3-inch (6.17 x 4.55 mm ) sized BSI-CMOS sensor .
Below you can see the TG-310 and S8400W sensor size comparison.
Olympus TG-310 and Fujifilm S8400W 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 compared to Fujifilm S8400W, it has potential to collect more light on pixel level hence have less noise in low light / High ISO images.