OGL Pocket GM Guide and Bestiary Question?

What's is the difference between the blue covered 392 page Pocket Games Master's Guide and the green covered 400 page Pocket GM's Guide and Bestiary? They both have the same MGP Code of 2222. I presume the latter is an update and includes some monsters but I cannot get confirmation of this from anyone.
They are the same product. Originally it was planned to be a GMs guide and bestiary but this would have beena massive tome so the book was changed to a GM guide only and the Bestiary is still being planned for a future release.