Canon PowerShot A540 vs Nikon D200 camera comparison
The same 2.5" lcd screen size is on both Canon PowerShot A540 and Nikon D200.
More details at its picture has Nikon D200 since it has 10.2Mpix at picture. Canon PowerShot A540 has less details and worse picture quality (6Mpix).
Canon PowerShot A540 has optical zoom of 4x and Nikon D200 doesn't have any. For Nikon D200 you should buy special external lenses. You choose lenses by your needs and preferences. That is the characteristic of some professional models.