Casio EX-H20G has a
14.0MP 1/2.3-inch (6.17 x 4.55 mm ) sized CCD sensor and features Exilim Engine HS processor. On the other hand, Sony WX70 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 EX-H20G and WX70 sensor size comparison.
Casio EX-H20G and Sony WX70 have the same 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 Casio EX-H20G has 14% larger pixel area compared to Sony WX70, it has potential to collect more light on pixel level hence have less noise in low light / High ISO images.