Nikon S70 has a
12.0MP 1/2.3-inch (6.17 x 4.55 mm ) sized CCD sensor and features Expeed processor. On the other hand, Sony TX20 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 S70 and TX20 sensor size comparison.
Sensor Size and Resolution Comparison image of Nikon S70 and Sony TX20 Cameras
Nikon S70 and Sony TX20 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 Nikon S70 has 32% larger pixel area compared to Sony TX20, it has potential to collect more light on pixel level hence have less noise in low light / High ISO images.
Sensor size sets the circle of confusion, so it drives how much depth of field each
of these bodies gives you at a given aperture. You can calculate it exactly for the
Nikon S70
or the
Sony TX20 ,
including hyperfocal distance.