Canon S120 has a
12.0MP 1/1.7-inch (7.44 x 5.58 mm ) sized BSI-CMOS sensor and features Digic 6 processor. On the other hand, Pentax E70 has a
10.0MP 1/2.3-inch (6.08 x 4.56 mm ) sized CCD sensor .
Below you can see the S120 and E70 sensor size comparison.
As seen above, Canon S120 has a 1.5x Larger sensor area than Pentax E70. 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.