Compared to other book-to-screen adaptations, The Devil Wears Prada is fairly faithful to the source, but there are still several ways the iconic movie differs. Based on the 2003 novel of the same name by author Lauren Weisberger, the 2006 movie starring Anne Hathaway, Meryl Streep, and Emily Blunt has only grown in popularity in the 18 years since its release. These actors gave excellent performances, and combined with the chaotic story from Weisberger, it's no wonder The Devil Wears Prada became a hit.
https://screenrant.com/devil-wears-prada-biggest-book-changes/