Difference in Official Guide 11th edition & 13th edition

Hi,

Please let me know what is the difference between 11th edition and the 13th edition of the Official guide. Is there only few questions added or a totally new question bank has been prepared. Actually I have the 11th edition. Please suggest what should I do?

Also I have the Verbal Review and the Math review - original edition and not the latest 1st edition.

Please guide. Thanks
Pooja