Nikon W300 has a
16.0MP 1/2.3 (6.17 x 4.55 mm ) sized sensor . On the other hand, Pentax W80 has a
12.0MP 1/2.3-inch (6.08 x 4.56 mm ) sized CCD sensor .
Below you can see the W300 and W80 sensor size comparison.
Nikon W300 and Pentax W80 have almost the same sensor size, so neither of them has any significant advantage over the other in terms of providing control over depth of field when used with the same focal length and aperture.