If you're worried about malicious differences, "regular" PDFs are worse. As noted in the article, it is extremely difficult to figure out the original text giv

If you're worried about malicious differences, "regular" PDFs are worse. As noted in the article, it is extremely difficult to figure out the original text given only a "normal" PDF, so you end up using a lot of heuristics that sometimes guess correctly. There's no guarantee that you'll be able to extract the "original text" when you start with an arbitrary PDF without embedded data. So if you're extracting text, neither way guarantees that you'll get "original text" that exactly matches the displayed PDF if an attacker created the PDF. That said, there's more you can do if you have an embedded OpenDocument file. For example, you could OCR the displayed PDF, and then show the differences with the embedded file. In some cases you could even regenerate the displayed PDF & do a comparison. There are lots of advantages when you have the embedded data.