N,
Thanks for reading our book! Nearly 10 years have passed since Matt published 80/20 Running, and we’ve completely re-written the run plans 4 times since then. I regret there is no change log, and I can’t specify the difference other than another 10 years of accumulated learning in running best-practices are now included in the new plans. The old book plans are great, the new plans are better.
Also note that the while the run workouts from the book are similarly named to the ones in the free run library, they are not the same workouts. Meaning, you can’t actually replicate the book plans using the library. See the full Q&A on that workout library page for a description and options.
David