Both Samsung HZ25W and Sony A7S II have 12.0 MP resolution sensors but Samsung HZ25W's sensor is 1/2.3-inch (6.08 x 4.56 mm ) and Sony A7S II's sensor is Full frame (35.6 x 23.8 mm ).
Since Sony A7S II'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 Samsung HZ25W.
Below you can see the HZ25W and A7S II sensor size comparison.
As seen above, Sony A7S II has a 30.6x Larger sensor area than Samsung HZ25W. 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.