I'm sure John will be able to clear this up a bit better than me as he has far more experience in this field than myself, but this is the problem with referring to species by common names because they differ from place to place.

As monitor lizard keepers it becomes so important to refer to a species by its latin name because animals from the same species can differ so greatly just from locality and sub species, like the rock monitor (Varanus albigularis). Its commonly know as the rock monitor, Southern African rock monitor, black throat, white throat, cape rock monitor, veldt leguanna and many more. You can imagine the confusion that takes place when trying to get that sorted out... And I won't even get started on the Indonesian tree monitor species