Answer:
1. The movie puts you more in the vision of the jurors at times. Ways they do that is by moving the camera like you are walking through the building. This is different then reading their lines in the play from a possibly more detached perspective.
2. The movie actually shows the boy, rather than how you only read mentions of him in the book. This possibly humanizes him more to the watcher or possibly makes them think more on if he actually did it based on looking at him.
3. The movie also possibly shows more of Juror 3's reactions and emotions than reading them in a play had done, like how he quietly walks out the door with the torn-up photo of his son left behind, which helps the watcher understand why he changes his mind in the end and generally enhances his character.
Step-by-step explanation:
I think you should watch the movie maybe, just to see it, I suppose.