Both Pentax K10D and Canon A495 have 10.0 MP resolution sensors but Pentax K10D's sensor is APS-C (23.5 x 15.7 mm ) and Canon A495's sensor is 1/2.3-inch (6.17 x 4.55 mm ).
Since Pentax K10D's has a larger sensor area with the same resolution, this means that it also has a larger pixel area hence better light collecting capacity for a given aperture compared to Canon A495.
Below you can see the K10D and A495 sensor size comparison.
As seen above, Pentax K10D has a 13.1x Larger sensor area than Canon A495. 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.