I have the old versions of both, and the new versions of both. The differences are almost non-existant. I didn't read through every page, but just glancing through them they appear almost identical. I gave the new versions to my kids so they could learn. I did not feel that I was giving away anything that I didn't already have. I personally would not repurchase the book unless your older copies are starting to fall apart. I agree that these are very good books, but don't expect the new to add much over the old.