Both Panasonic ZS35 and Panasonic ZS45 have 16.0 MP resolution sensors but Panasonic ZS35's sensor is 1/2.3-inch (6.08 x 4.56 mm ) and Panasonic ZS45's sensor is 1/2.33 (6.08 x 4.56 mm ).
Since Panasonic ZS45'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 ZS35.
Below you can see the ZS35 and ZS45 sensor size comparison.
Panasonic ZS35 and Panasonic ZS45 have the same sensor sizes so they will provide same level of control over the depth of field when used with same focal length and aperture.