Both Canon SX200 IS and Panasonic ZS50 have 12.0 MP resolution sensors but Canon SX200 IS's sensor is 1/2.3-inch (6.17 x 4.55 mm ) and Panasonic ZS50's sensor is 1/2.3 (6.17 x 4.55 mm ).
Since Panasonic ZS50'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 SX200 IS.
Below you can see the SX200 IS and ZS50 sensor size comparison.
Sensor Size and Resolution Comparison image of Canon SX200 IS and Panasonic ZS50 Cameras
Canon SX200 IS and Panasonic ZS50 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.