What is new in the 7th edition of A Writer's Reference?

I have a friend who could really use the help of this book, but I only have the 4th edition. Does anyone know what changes have been made or where I can find out? I don’t want to give her an out of date book, but I also don’t want her to miss out on a useful tool if the basics remain the same. I can’t imagine MLA or APA have changed all that much, but I could be wrong.

No, she can’t afford to just go buy the new one.