Pentax WS80 has a
10.0MP 1/2.3-inch (6.17 x 4.55 mm ) sized CCD sensor and features Prime processor. On the other hand, Pentax WG-2 has a
16.0MP 1/2.3-inch (6.17 x 4.55 mm ) sized BSI-CMOS sensor .
Pentax WG-2's sensor provides 6MP more than Pentax WS80's sensor, which gives a significant advantage in real life. You can print your images larger or crop more freely.
On the other hand, please keep in mind that Max sensor resolution is not the only determinant of resolving power. Factors such as the optical elements, low pass filter, pixel size and sensor technology also affects the final resolution of the captured image.
Below you can see the WS80 and WG-2 sensor size comparison.
Pentax WS80 and Pentax WG-2 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.