It seems the wrong picture lacks on ambient light and only shows the specular reflection light. Maybe the terrain is lighted by more than the three lights supported by the specBump shader and the first three lights are far enough to be darken near to black so there is no ambient lighting. I am not sure about the following but probably the light list is sortered by the distance to the entitys origin each frame, so in the case of a model used as a terrain the origin can be pretty far and the lights near its origin are the ones passed to the shader. Probably the terrains light list is sorted by the distance to the rendered view: a good reason for the existence of terrains (in addittion to a better polygon culling by chunks)

Salud!