Nikon L31 has a
16.0MP 1/2.3' (6.17 x 4.55 mm ) sized CMOS sensor . On the other hand, Olympus VG-110 has a
12.0MP 1/2.3-inch (6.17 x 4.55 mm ) sized CCD sensor and features TruePic III processor.
Below you can see the L31 and VG-110 sensor size comparison.
Nikon L31 and Olympus VG-110 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-110 has 35% larger pixel area (2.38µm2 vs 1.76µm2) compared to Nikon L31, it has larger pixel area to collect light hence potential to have less noise in low light / High ISO images.