With adaptations coming out so often, fans know by now that not everything from the book can make it into the movie and the aspects that do appear sometimes are changed. All of this rings true for “Love, Simon,” the film adaptation of Becky Albertalli’s 2015 novel, “Simon vs. the Homo Sapiens Agenda,” about a gay teenager named Simon who finds love and finds himself.

The film comes out Friday, but if you want a spoiler-filled heads up about what changes to expect, here are 10 major differences between “Simon vs. the Homo Sapiens Agenda” and “Love, Simon,” its movie counterpart:

1. Simon’s family

Book: Simon has two sisters, a little sister, Nora, and an older sister, Alice, who’s away at university, but comes back once in a while to see her family.

Film: Only Nora (Talitha Eliana Bateman) exists and she appears to be a little bit younger than in the book. She also has a newfound love of cooking that wasn’t in the novel version. Plus, with Alice gone, the character of her boyfriend, Theo, is gone, as well.

2. Simon

Book: He’s a high school junior in the novel and though not mentioned throughout the book that he wears glasses, it’s specifically written towards the end that Simon is wearing contacts for the play.

Movie: Simon (Nick Robinson), now a high school senior, is not seen wearing glasses in the film.

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Simon (Nick Robinson) walks his way towards school while others look on in this photo from “Love, Simon.” Ben Rothstein/Twentieth Century Fox

3. The emails

Book: Simon finds a blog on the CreekSecrets Tumblr page from someone calling themself Blue, coming out as gay. Relating to the words in the post, Simon anonymously comments “THIS” and his email address, which is hourtohour.notetonote@gmail.com, in the hopes that Blue would contact him. He did, a week later.

Once the two begin emailing, with Simon going by the name Jacques, Blue reveals he knew he liked guys when he became attracted to an older male at a family wedding. Simon shares that his first girlfriend was in 8th grade, but he ditched her at a dance.

Movie: Simon finds the blog all the same, but instead of commenting, he reaches out to Blue directly, sending him the first email from the address frommywindow1@gmail.com, but still calling himself Jacques. Though this is a different name from the book, original fans will be happy to spot the Easter egg of the words “hour to hour note to note” on Simon’s bedroom chalkboard. Plus, Blue has the same email, bluegreen118@gmail.com, in both versions.

Blue explains that Jon Snow was the cause of his sexual awakening, while Simon’s ditched first girlfriend at a dance in his sophomore year.

4. Halloween Party

Book: Garrett throws a Halloween party and Simon attends as a Dementor because he loves “Harry Potter” while Leah goes as Tohru from the “Fruits Basket” series. During the party, Nick plays his guitar for everyone.

Movie: Bram (Keiynan Lonsdale) is the one throwing the party, which Simon and Leah (Katherine Langford) wear a two-person costume to. The friends go as John Lennon and Yoko Ono. Meanwhile, Nick’s (Jorge Lendeborg Jr.) guitar-playing is nowhere to be seen in the whole movie.

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Simon and his friends head to a Halloween party in this scene from “Love, Simon.” Ben Rothstein/Twentieth Century Fox

5. Abby’s home

Book: Abby’s lives farther away from the school than everyone else and it takes her an hour to get there on the bus.

Movie: She lives a lot closer and is easily picked up by Simon and his friends on the way to school.

6. Vice Principal Worth

Book: This character does not exist.

Movie: Played by Tony Hale, this character adds a little extra punch of fun and laughter to the mix.

7. Leah’s crush

Book: Leah has a big, unspoken crush on Nick and partially dislikes Abby because of how close she’s getting with him. Simon can tell she has these feelings, but he knows not to bring it up.

Movie: Simon still believes that Leah likes Nick, but, in actuality, it’s him that she’s had a crush on. Not knowing this and trying to fix her up with Nick, in order to help Martin (Logan Miller) get with Abby (Alexandra Shipp), Simon encourages Nick to go out with Leah before the Homecoming game.

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Nick Robinson and Katherine Langford as Simon and Leah in “Love, Simon.” Ben Rothstein/Twentieth Century Fox

8. Homecoming week and game

Book: Leading up to the big football game, all of the students participate in spirit week, with each day bringing different costumes with it. Some of the days include Gender Bender Day, where the soccer stars dress up as cheerleaders and Music Day, where the juniors’ theme is country music and Simon wears a bandana and a cowboy hat.

The game starts at 7 p.m. on the Friday of that week and there is a big parade at 6 p.m. right before it. During the game, the stadium is packed and Simon’s not able to sit with Nick and the soccer players, so he goes to his drama friends.

Movie: There is no spirit week, no parade and no packed crowd, making it easy for Simon to sit with his usual friends. There is, however, a grand gesture from Martin, who’s dressed up as the school’s mascot in the middle of the football field, declaring his love for Abby.

9. Simon’s “coming out”

Book: In mid-December, Simon tells Abby that he’s gay on the way home from studying for the play at a Waffle House. A couple weeks later, on Dec. 24, Nick and Leah come by his house to try to talk with him about something, but it doesn’t really go as planned. Later that evening, Nora shows him a new CreekSecrets post, which outs him as and references Blue slightly. He receives a text from Abby to make sure he’s okay.

The following day, on Christmas morning, Simon comes out to his family while they’re all opening gifts. It’s not until New Year’s Eve, when Abby, Nick and Leah are over, that he comes out to the latter two.

Movie: Simon tells Abby the same way in early December, but Leah is the one who tells Simon to look at CreekSecrets later on. In the post outing him, Blue isn’t just mentioned, there are screenshots of their email exchanges. After seeing it, Nick and Leah text Simon, asking him to go on a walk, but he just ignores it all. Simon comes out to his family on Christmas, but he doesn’t hang out with his friends on New Year’s Eve. Instead, Abby and Nick hang out themselves and get together.

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Simon’s family spending time together in “Love, Simon.” Ben Rothstein/Twentieth Century Fox

10. The big reveal and ending

Book: Upon returning to school after the holiday break, Simon is bullied by some footballers and a few other random students. Turning to the one person he hopes would understand, Simon messages Blue to ask him to finally meet in person and though Blue guesses who the boy he’s been messaging is by now, he still doesn’t want to meet.

That said, he does leave an Elliott Smith shirt for Simon at school, which means a lot because he’s one of Simon’s favorite singers. He’s the one who sang the lyrics that made up his email address, and Simon always said that he wasn’t sure he should wear a concert shirt without actually attending the event.

After a few more days, the two stop emailing because Simon believes he doesn’t like him anymore since he knows who he is, but still doesn’t want to meet. Eventually, at the end of January, Simon emails Blue and invites him to a carnival to finally meet. When Simon goes to put on the Elliott Smith shirt, he finds that Blue had attached a sweet note to it this whole time, which included his phone number.

Simon goes to the carnival and sits for a while, with no Blue in sight. When the event is starting to close up, he heads to the Tilt-A-Whirl, sits alone and just before the ride starts, Bram sits next to him and reveals that he’s Blue.

Over the next few days, they decide to be boyfriends, they change their Facebook statuses and have an incredibly sweet lunch break from school where they head to the grocery store, buy their favorite food, Oreos, and milk and sit in the car together while the rain comes down.

The book winds down with a talent show, which features Nora and Leah in a band and Abby dancing in her own performance. Afterwards, while his family goes out to dinner, Simon and Bram have the former’s house to themselves before his mom comes home and the book ends.

Movie: After seeing the post, Blue tells Simon that he can’t email him anymore and closes his account. With no way to invite him to the carnival by email or phone, Simon decides to write his own blog post. He chronicles his thoughts on what’s been going on in his life and asks Blue to meet him at the event at the Ferris Wheel. Though no Elliott Smith shirt to wear or mention of him, there’s an Easter egg of a poster of him on Simon’s bedroom wall.

When at the fair, Simon buys a lot of tickets to the ride and just sits on it as the time passes and as students from his school stand around and watch him, all waiting to see who will show up. Finally, with only about one ride left, Bram shows up, tells him that he’s Blue and the two kiss at the top while everyone cheers from down below.

The film wraps up as other students begin confessing things on the blog, while Simon once again sets out in his car heading to school, picking up his friends — Nick, Leah and Abby — and coffees along the way. Though this time, Bram is there for the ride.

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Nick Robinson stars as Simon in “Love, Simon.” Ben Rothstein/Twentieth Century Fox

Aside from all of these differences, there were also plenty of scenes, characters and storylines that were just flat-out missing. Leah’s friends Morgan and Anna were absent. There’s no mention of Simon’s birthday and the lunchtime cake that comes with it. Plus, without the scene of Abby and Nick taking Simon to a gay bar, the movie is also without the guy he meets there, Peter. And that's just a few of the pieces that were left out in the move from page to screen.

There are always going to be things changed when books are adapted into films, but what’s important is that the overall story and heart of the novel is kept. “Love, Simon” which opens in theaters on Friday, did just that.