Canon SX20 IS has a 12.0MP 1/2.3-inch (6.17 x 4.55 mm ) sized CCD sensor and features Digic 4 processor. On the other hand, Sony HX100V has a 16.0MP 1/2.3-inch (6.17 x 4.55 mm ) sized BSI-CMOS sensor and features BIONZ processor.
Below you can see the SX20 IS and HX100V sensor size comparison.
Canon SX20 IS and Sony HX100V have 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 SX20 IS has 32% larger pixel area compared to Sony HX100V, it has potential to collect more light on pixel level hence have less noise in low light / High ISO images.