Canon SX120 IS has a
10.0MP 1/2.5-inch (5.744 x 4.308 mm ) sized CCD sensor and features Digic 4 processor. On the other hand, Olympus E-PL1s has a
12.0MP Four Thirds (17.3 x 13 mm ) sized CMOS sensor and features Truepic V processor.
Below you can see the SX120 IS and E-PL1s sensor size comparison.
As seen above, Olympus E-PL1s has a 9.1x Larger sensor area than Canon SX120 IS. 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.