Luckily, these are PDF documents so you can take advantage of the Document > Compare Documents feature and let Acrobat do the work for you.
Acrobat will ask you to select two documents that you wish to compare (called older and newer document). Acrobat wants a hint as to whether its focus will be graphics or text or both so you will then select the type of document your work resembles (such as Reports, spreadsheets, magazine layouts, etc).
A new PDF file is created for you, called [Compare New]your_document's_name.pdf. This special PDF document starts off with a summary report, naming the old and new document's file name, some basic facts (such as "No pages were deleted"), and a basic legend of indicator marks. You will also see a Compare Panel open on the left. Pages that have differences are marked with a purple box. On the pages with differences from version to version, comments are inserted to point out these differences. You will find a floating legend with explains the different color comment types--blue for inserts, red for deletions, etc.
There is no more guesswork. Not even the smallest difference between the two documents will elude you. Another Acrobat gem!