Both Pentax WG-3 and Panasonic TS6 have 16.0 MP resolution sensors but Pentax WG-3's sensor is 1/2.3-inch (6.17 x 4.55 mm ) and Panasonic TS6's sensor is 1/2.33' (6.08 x 4.56 mm ).
Since Pentax WG-3'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 Panasonic TS6.
Below you can see the WG-3 and TS6 sensor size comparison.
Pentax WG-3 and Panasonic TS6 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.