8. Structure (mild geek warning)
Ted Chiang builds considerable structure into his story - for example by my count the story is divided into 42 sections (6×7). There are 112 alien spaceships in orbit (16×7). The story also has a ring structure in that it opens and closes with the same event - the couple heading for bed and the conception of their daughter. (Ring structure, and its more complex cousin chiasmus, were used extensively in ancient literature but are much less frequently found nowadays).
Some of this is kept in the film - for example the ring structure. Some is discarded - for example the number of prose sections. And some is altered - for example there are just 12 ships, which come down from orbit to ground level... which does allow the very cool "each team has 1/12 of the whole" twist near the end.
Does this just reflect the strengths and weaknesses of each of the two storytelling media? Or is something else at work? And most importantly, do you appreciate and respond to literary structures or not?