Nikon S570 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 W330 has a
14.0MP 1/2.3-inch (6.17 x 4.55 mm ) sized CCD sensor .
Below you can see the S570 and W330 sensor size comparison.
Nikon S570 and Sony W330 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.