Sony W320 has a
14.0MP 1/2.3-inch (6.17 x 4.55 mm ) sized CCD sensor . On the other hand, Sony WX50 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 W320 and WX50 sensor size comparison.
Sony W320 and Sony WX50 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 Sony W320 has 14% larger pixel area compared to Sony WX50, it has potential to collect more light on pixel level hence have less noise in low light / High ISO images.