I am not sure this is the right place for such subject.
DoF is a forum dedicated to industrial robotics, especially collaborative robotics.
I will try to answer the question just for the fun :)
Rc vehicle said for radio control car. This is a unnamed ground vehicle control by a distant operator using radio frequency signal.
Unnamed ground vehicle stand for any ground vehicle without human pilot. Could be an autonomous vehicle for example.
What is the difference between R C cars and unmanned ground vehicle ?