Pro's use the sub D200 line of cameras however. I think the major difference between the cameras (at least based on the information in the B&HPhoto sourcebook), is the function of the individual cameras and their intended use. Anyone who takes a D2Hs or D2Xs out as a "I like photography, it's my hobby" camera, has been sorely sold a limited edition Ducati Monster when all they wanted was a reliable commuter scooter.
The sub lines are perfectly capable of creating professional quality shots, just like my consumner laptop is capable of creating pro level CGI - its just one will do it with greater ease and flexibility than the other.