Canon S200 has a
10.0MP 1/1.7 (7.44 x 5.58 mm ) sized CCD sensor and features Digic 5 processor. On the other hand, Olympus XZ-2 iHS has a
12.0MP 1/1.7-inch (7.44 x 5.58 mm ) sized CMOS sensor .
Below you can see the S200 and XZ-2 iHS sensor size comparison.
Canon S200 and Olympus XZ-2 iHS 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 Canon S200 has 18% larger pixel area compared to Olympus XZ-2 iHS, it has potential to collect more light on pixel level hence have less noise in low light / High ISO images.