Both Samsung WB850F and Panasonic ZS45 have 16.0 MP resolution sensors but Samsung WB850F's sensor is 1/2.3-inch (6.17 x 4.55 mm ) and Panasonic ZS45's sensor is 1/2.33 (6.08 x 4.56 mm ).
Since Samsung WB850F'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 ZS45.
Below you can see the WB850F and ZS45 sensor size comparison.
Samsung WB850F and Panasonic ZS45 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.