Olympus SH-2 has a
16.0MP 1/2.3' (6.17 x 4.55 mm ) sized BSI-CMOS sensor and features TruePic VII processor. On the other hand, Casio EX-S200 has a
14.0MP 1/2.3-inch (6.17 x 4.55 mm ) sized CCD sensor and features Exilim Engine 5.0 processor.
Below you can see the SH-2 and EX-S200 sensor size comparison.
Olympus SH-2 and Casio EX-S200 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 Casio EX-S200 has 14% larger pixel area (2.01µm2 vs 1.76µm2) compared to Olympus SH-2, it has larger pixel area to collect light hence potential to have less noise in low light / High ISO images.