You may have been wondering about the difference between Chiang's novella, "Story of Your Life," and the movie that is based on the story, Arrival (2016). The most immediately apparent difference between the two works is their title—this is probably because Arrival has more marketing appeal. "Story of Your Life" works for a novella, but it might be too clunky for a movie poster.
The movie adaption, directed by Denis Villeneuve, remains faithful to Chiang's story but adds elements that keep the plot of the movie moving. For example, the movie does not specify precisely when the present is. In contrast, the novella tells us that we are situated in the present, and the context of that present, within the first few paragraphs of the story: "Right now your dad and I have been married for about two years, living on Ellis Avenue; when we move out you'll still be too young to remember the house, but we'll show you pictures of it, show you stories about it. I'd love to tell you the story of this evening, the night you're conceived" (91). In other words, when we are reading the story, we know that in the present we are situated in the night Dr. Banks's daughter is conceived. The heptapods have visited in the past, and the daughter's life, which Dr. Banks will narrate, is waiting in the future.
In contrast, in the film, we are made to assume that Dr. Banks's daughter has already died. We do not know that this event is yet to come until later in the film, when we learn that Dr. Banks has a new way of seeing time. Until that moment, we assume that time in the movie works as we know it to work in our lives: sequentially, with one event coming after another. The story, therefore, is much more straightforward about the chronology of Louise's experiences—the fact that events in the future use the future tense and evens in the past use the past tense help to clarify this.
Another difference between the film and the story is that the linguistic properties of Heptapod A and Heptapod B are examined in more depth in the story. In "Story of Your Life," not only do we learn the rules that govern each language, but we watch Dr. Banks go through the discovery process as she would if she were conducting fieldwork in human language. This teaches us not only about heptapods, but also about the field of linguistics—how it works, where meaning is found, how information is gathered, etc.
Some of the differences between the story and the film are attempts to create tension on the part of the filmmakers. For example, the daughter dies of a terminal illness, rather than a rock-climbing accident, in the film. The daughter is also younger, probably around fourteen or fifteen years old, when she dies in the film. This heightens the emotional effect of the daughter's death for viewers. Additionally, in the film, Dr. Donnelly leaves Dr. Banks because he realizes that she knew what will happen to their daughter—this is not made explicit in the novella. Another major difference between the story and the film is Dr. Banks's character—Dr. Banks is quick to crack jokes in the novella; in the movie, however, she is much more serious.
If you read Chiang's novella and watch the movie, ask yourself: why were these changes made? It is clear that Heisserer wanted to stay as faithful to the original material as possible and that his movie is a "labor of love." Why does he make the changes that he does? Do they have a particular effect? What story do these changes tell? Which version do you prefer?