Olympus Tough-3000 has a
12.0MP 1/2.3-inch (6.08 x 4.56 mm ) sized CCD sensor and features TruePic III processor. On the other hand, Olympus TG-320 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 Tough-3000 and TG-320 sensor size comparison.
Olympus Tough-3000 and Olympus TG-320 have almost the same sensor size, so neither of them has any significant advantage over the other in terms of providing control over depth of field when used with the same focal length and aperture.