The biggest difference of all, is that The Dark Tower does not introduce Eddie Dean and Susannah Walker.
Therefore, then, we are to assume that The Dark Tower Movie is just another iteration of Roland’s tale, with changes happening as a result of his actions.
When Roland reaches the Dark Tower in the final novel, he finds that his journey begins over again, and again, and again.
After Jake dies in ‘The Dark Tower” (book), Roland discovers he shares a telepathic connection with three New Yorkers.