The 8 biggest differences between the 'It Ends With Us' book and movie

Blake Lively as Lily Bloom in "It Ends With Us."Jojo Whilden/Sony Pictures Ent.

• Warning: This article contains major spoilers for "It Ends With Us."
• The Blake Lively movie is an adaptation of Colleen Hoover's novel of the same name.

The book-to-screen adaptation of one of BookTok's most popular reads, "It Ends With Us," was released in theaters on Friday.

Based on Colleen Hoover's 2016 novel of the same name, the film stars Blake Lively as florist Lily Bloom, whose chance meeting with charming neurosurgeon Ryle Kincaid (played by Justin Baldoni) sparks an intense connection.

As Lily begins to see sides of Ryle that remind her of her parents' relationship, a figure from her teenage years also reenters the picture: Atlas Corrigan (Brandon Sklenar), her first love.

As with any book-to-screen adaptation, there have been changes — some big, some small.

"Every change that we made was christened by Colleen herself, and none of the changes were made lightly," screenwriter Christy Hall told Business Insider in an interview.

"But this is, I feel like this is the absolute best offering that we could give," she added.

Here are eight of the biggest differences between the "It Ends With Us" book and the movie.