lol - confusing isn't it !!! I have a book by Phillipe de Vosjoli and Robert Mailloux called General care and Maintenance of Bearded Dragons - I honestly thought when I first began that there was one type and one type only - then I opened the book lol
This is what they list:-
AN OVERVIEW OF THE DRAGONS IN THE GENUS Pogona
The following species of Pogona are currently recognised:
Bearded dragon (Pogona barbata)
Lawson's or Rankin's dragon (Pogona henrylawsoni)
Pogona microlepidota - they don't list a common name for this one

Western bearded dragon (Pogona minima)
Dwarf bearded dragon (Pogona minor)
North-West bearded dragon (Pogona mitchelli)
Nullarbor bearded dragon (Pogona nullarbor)
Inland or Central bearded dragon (Pogona vitticeps)
Obviously, this book is pretty old now and there may be more species listed - hope this gives an insight as to the different species out there (although I have never heard of most of them lol)