The new book is intended specifically for athletes who want to use the lifts in their training, but don't want to commit huge amounts of time and energy learning them, knowing everything about them, etc. So the biggest difference is that it's far more concise - about 120 pages vs 400+ - to keep the process and presentation as simple and straightforward as possible. This was tough for me because I can be a windbag, but I went out of my way to say as little as I thought was necessary to adequately understand enough and learn properly and safely. The teaching/learning progressions are different than in my old book for this reason, and the programming section is brief.
Joe Kenn's book is probably one of the most underrated texts out there. It's great if you're programming for athletes, especially teams/groups and especially power-oriented athletes like footballers and the like. He lays out a really sharp system that allows you to be very precise and thorough but flexible w exercise selection and the like to make sure the training is optimized for the athlete(s) in question. Definitely worth the money. I have literally turned down consulting jobs and told the client to instead just buy that book more than once before.