Casio EX-100 has a 12.0MP 1/1.7" (7.44 x 5.58 mm ) sized CMOS sensor . On the other hand, Pentax WS80 has a 10.0MP 1/2.3" (6.17 x 4.55 mm ) sized CCD sensor and features Prime processor.
Below you can see the EX-100 and WS80 sensor size comparison.
As seen above, Casio EX-100 has a 1.5x Larger sensor area than Pentax WS80. Larger sensors give photographer more control on the depth of field and blurry background compared to smaller sensor when shot in same focal length and aperture.