Nikon S100 has a
16.0MP 1/2.3-inch (6.17 x 4.55 mm ) sized CMOS sensor and features Expeed C2 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 S100 and XZ-2 iHS sensor size comparison.
As seen above, Olympus XZ-2 iHS has a 1.5x Larger sensor area than Nikon S100. Larger sensors give photographer more control on the depth of field and blurry background compared to smaller sensor when shot in same focal length and aperture.