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, Fujifilm X20 has a 12.0MP 2/3-inch (8.8 x 6.6 mm ) sized CMOS X-TRANS II sensor and features EXR Processor II processor.
Below you can see the SX120 IS and X20 sensor size comparison.
As seen above, Fujifilm X20 has a 2.3x 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.