Olympus TG-610 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 S8100fd has a
10.0MP 1/2.3-inch (6.17 x 4.55 mm ) sized CCD sensor .
Below you can see the TG-610 and S8100fd sensor size comparison.
Olympus TG-610 and Fujifilm S8100fd 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.