Both Samsung NX3000 and Samsung NX200 have 20.0 MP resolution sensors but Samsung NX3000's sensor is APS-C (23.5 x 15.7 mm ) and Samsung NX200's sensor is APS-C (23.5 x 15.7 mm ).
Since Samsung NX200'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 NX3000.
Below you can see the NX3000 and NX200 sensor size comparison.
Samsung NX3000 and Samsung NX200 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.