Olympus VG-120 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, Nikon AW120 has a
16.0MP 1/2.3-inch (6.17 x 4.55 mm ) sized CMOS sensor .
Below you can see the VG-120 and AW120 sensor size comparison.
Olympus VG-120 and Nikon AW120 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 VG-120 has 15% larger pixel area compared to Nikon AW120, it has potential to collect more light on pixel level hence have less noise in low light / High ISO images.