Difference between ACT Red Book 3rd Edition and 4th Edition?

Hi! Although I’ve read a lot of threads on here before, this is my first time posting :smiley:
I got the 3rd edition of The Real ACT Prep Guide from my friend and I recently found out that it’s outdated. What are the differences between this and the new book? Is it necessary that I buy the new 4th edition in order to do well on the test? Are there other ACT books you recommend to supplement the 3rd edition that I already have? Any other tips you have about studying for the ACT would be greatly appreciated. :slight_smile:
I have not started studying for the ACT yet, but I have taken the SAT twice. I didn’t do as well as I hoped for both times (I did worse the second time I took it!), so I thought I would try to study for the ACT this summer instead.