Sony H50 has a
9.0MP 1/2.3-inch (6.17 x 4.55 mm ) sized CCD sensor . On the other hand, Sony H200 has a
20.0MP 1/2.3-inch (6.17 x 4.55 mm ) sized CCD sensor .
Sony H200's sensor provides 11MP more than Sony H50's sensor, which gives a significant advantage in real life. You can print your images larger or crop more freely.
On the other hand, please keep in mind that Max sensor resolution is not the only determinant of resolving power. Factors such as the optical elements, low pass filter, pixel size and sensor technology also affects the final resolution of the captured image.
Below you can see the H50 and H200 sensor size comparison.
Sony H50 and Sony H200 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. On the other hand, since Sony H50 has 69% larger pixel area compared to Sony H200, it has potential to collect more light on pixel level hence have less noise in low light / High ISO images.