There are many key differences between the It movies and the book. Though a handful of these differences are easy to miss, they impact the story in different ways.

One of the prime differences is the time each story takes place in. In the book during the chapters where the main characters are children, the setting is in 1957 and 1958. Once they return, as adults, to kill Pennywise (the villain), it is 1985. In the movies, they take on Pennywise as children in 1988 and 1989.

Another difference focuses more on the characters of the plot. In the book, Patrick Hockstetter is much more unpleasant. Not only does he bully and beat Eddie, but he keeps dead flies in his pencil box and kills dogs and cats for fun (then later stores them in a freezer). Furthermore, Marsh was never the “damsel in distress” in the novel, so the others didn’t need to save her. The movie, however, changed some of the plotlines, making her the “damsel in distress.” This is how the children end up being lured back into the sewers. 

Lastly, the book has much more detail compared to the movies. It’s as if they skipped details because of budget and time. This seems to be the case for many book-to-movie adaptations. Overall, the book and movie are both good, but the book has many details and areas that were not explored. Many people would love to see those areas explored, so let’s hope they get remakes in the future!