What actually differs between Elementor and Divi?
Where each one keeps your layout is the difference that matters. Elementor stores the design as structured data in a separate field attached to the post; Divi writes it into the body of the post itself. That sounds like an implementation detail, and it is the most consequential difference between them, because it decides what you see on the day the builder is switched off: an empty page in one case, a page full of visible markup in the other. Neither outcome is good and they are not the same problem, which is why the answer to "can we leave later" differs by builder rather than being a general truth about builders.