system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: What makes 70mm film screenings different? (i.e. Dunkirk)
gpt
For one, it's not a digital projection.  Most movies you go see in a theater are projected digitally, but if you had gone 15 or so years ago, they would have all been projected with film.  There is an ongoing debate about which is better.  Digital tends to show a cleaner picture, but the detail is limited to a certain resolution and film tends to have richer colors and blacks, but with some minor imperfections in the picture.  It's sort of similar to the debates about whether sound quality is better on vinyl records than it is on digital files.  

Anyway, if you had gone to see a movie back in the day, in most cases it was on 35mm film.  Dunkirk is being shown on some screens in 70mm film which means that the individual frames are larger and thus have more detail.