1. Setting: The book is primarily set in New York City, while the movie is mostly filmed in San Francisco and Los Angeles.
2. Characters:
- Mia Thermopolis: In the book, Mia is portrayed as taller, more outspoken, and sarcastic. She has a stronger personality compared to the movie's portrayal.
- Michael Moscovitz: The book's Michael is Mia's best friend since childhood, while the movie introduces him as a new student.
- Lilly Moscovitz: In the book, Mia's best friend is her younger sister, Lilly, whereas the movie creates the character of Lilly as a separate person.
- Mia's parents: The book explores Mia's complex relationship with her bohemian artist mother, Helen. In the movie, her mother is deceased, and her father, Philip, takes a more prominent role.
3. Plot Elements:
- Mia's transformation: The book takes more time to develop the process by which Mia transforms into a princess, including the challenges she faces with etiquette training.
- Queen Clarisse: In the book, Mia's grandmother is named Clarisse Renaldi, while in the movie, she is named Queen Clarisse Renaldi.
- Michael and Josh: The movie introduces a love triangle between Mia, Michael, and a new character, Josh Bryant, while the book's primary focus is on Mia and Michael's relationship.
- Political Intrigue: The book also delves into political aspects as Mia must navigate the Genovian royal court and deal with potential usurpers.
While the movie follows the general outline of the book's plotline, it makes notable changes to certain characters, their relationships, and some narrative elements. Nevertheless, both the book and the movie capture the essence of a teenage girl's transformation and journey of self-discovery as she embraces her royal destiny.