...May I ask a question? Were your two books purchased from Amazon? Or pdf books from Apress? Thanks..!
Amazon as physical books, with paper pages
I don't care for e-books
I like to take notes and scribble in the margins, and use an actual physical book-mark.
Moreover, your two books are new editions for GM 8.0 or old editions for GM7.0? Thanks again.!!! 
The first book I got back in 2007, that's the one I am going through right now. I believe it covers GMv6 (and 7 ?) as all the references seem to hint at it being v6 (or at least the file extensions, *.gm6).
As I said, I have not bumped into any issues with incompatibilities using that book with my registered GM8.1
The second book is as up to date as possible (well ... up to an including gm8 ?) I am mainly looking forward to the last section of it, the pirates game as that introduces you to a "different way" of using sprites, almost like
shadow puppetry.
I don't know if either book has been edited, to reflect any changes/additions, since their first publication years. Maybe they are both "first editions" i.e. without any new changes, or perhaps there have been other editions since they first came out. It is quite possible, though I have no idea about that. I do know that the aPress site has a special section for their books where you can look up changes to code or the actual full code, and other changes which the authors may have posted, though I have not looked at if these two books in particular offer that on the aPress site. It is easy enough to contact not only aPress or the authors about this, if you are in dire need of knowing if they have updated their books.
BTW Both of my books are "first editions".