Canon S95 has a
10.0MP 1/1.7-inch (7.44 x 5.58 mm ) sized CCD sensor and features Digic 4 processor. On the other hand, Canon ELPH 500 HS has a
12.0MP 1/2.3-inch (6.17 x 4.55 mm ) sized BSI-CMOS sensor and features DIGIC 4 with iSAPS technology processor.
Below you can see the S95 and ELPH 500 HS sensor size comparison.
As seen above, Canon S95 has a 1.5x Larger sensor area than Canon ELPH 500 HS. 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.