The text is theoretically the same. Although, of course, some will be more or less up-to-date than others:
- the print edition will be up to date as of when it was sent to the presses
- the kindle edition will be up-to-date as of when it was downloaded
- the website (and online guide on this forum) and the app should be right up to date.
The print edition will be as easy to read as a book. The downside is it takes up space and has weight for you to carry.
The kindle edition means reading on your phone but takes no space and has no weight. For me, that tends to make books worth reading on my phone on Caminos. But for others, the balance is different.
The app has the bonus of more useful maps, especially since they show where you are at the moment while on the Camino, allowing you to confirm at a glance whenever you are worried that you are on Camino. And if you find you are not, see exactly how to get back onto the Camino. For me, that's worth the price of admission itself. It also has the neat WhatsApp wizard to help you communicate with albergues via WhatsApp even if you don't know Spanish. It also has the comments from other pilgrims. I'm not sure if those are in the printed guide or Kindle version.
I'm sure
@wisepilgrim can correct me if I got anything wrong.