I see from Apple's own explanation on iBook updates that:
When an eligible book has an update, you'll see a badge with the number of available book updates. When you download a book update, your existing bookmarks, annotations, and notes are retained and carried over to the new version of your book. You can see what's included in an update by tapping What's New.
I cannot seem to find the "What's New" button to tap on any of the updates to my iBooks.... is it in My Library? Is it contained in the book itself? It's probably really obvious the second someone points it out...
