What both have in common
Paper or e-ink, you write by hand, and that changes how you think. You can't write down everything, so you choose, shorten and put things in your own words. Arrows, boxes and small sketches come along naturally.
Both also keep you away from the rest of screen life. A notebook has no notifications, and most e-ink tablets are deliberately plain. So the question is less "hand or keyboard" than: which tool fits your day? What research says about writing by hand, and what it doesn't, is in the guide Why writing by hand helps you remember.

