Every single word, sentence, and paragraph has been reviewed and rewritten where applicable. For some chapters, like those involving pattern matching and threading, this resulted in significant changes and revisions. For a few chapters, the changes are less noticeable. To answer your question, though, every chapter contains some amount of changes.
Writing the new book didn't just involve adding content, we need to refine and refactor content to match the Java 21 exam. This also meant streamlining/simplifying topics that don't feature as prominently on the exam anymore.