MGMAT guide books difference in editions

Hi. The biggest changes are the question tables since 4th edition is for the OG 12 and we are on OG 15 and about to get OG 16.
Also, you will get the IR book with 6th edition. I think you should get the new edition. And if you search, you will find 4th vs. 5th edition here too.

~~~ Comparison of the 5th edition vs 6th edition. ~~~
I have gone through all of the books and here is how it looks:
Overall, all books have undergone some degree of updating; not just slapping a new cover as some providers do, so you will be better of buying the 6th if you are deciding. If you own the 5th edition already, I would recommend getting only the IR and RC books, however as they have undergone the most transformation. The rest is organized better (more logical); it will help those who are short on time; the pages now also have more graphs, charts, and cheat sheets at the end (a number of books added this feature including Geometry and CR).
IR - substantial changes and improvements - the book needed them, and is now split by question type and organized a lot better
Quant - mostly minor updates (less than 10% new content)
RC - Major update
SC - Restructure with the main difference is that the idiom section is cut down and rewrite of most chapters (more than 20% of content updated)
CR - Improvements in text-heavy areas that put people to sleep before. Cheat sheets added after each chapter. I do like pre-thinking, however, in CR, so I still feel that CR book can be improved.