This list pertains to the books and the first movie. Don't even get me started on the second movie where she marries someone who ISN'T Michael Moscovitz. That's just absurd.
  1. Mia's hair color
    Mia is blonde in the books, but brunette in the movies.
  2. Setting
    The books take place in New York! The movie takes place in San Francisco
  3. Grandmère
    In the books, the dowager princess is a manipulative, sometimes cruel, snooty, borderline alcoholic. In the movie, she is Julie Andrews, and goes by Grandma.
  4. Daddy issues
    In the books, Mia's father has testicular cancer, but is alive. In the movie, his death is, more or less, the inciting incident.
  5. Name
    In the book, Mia's full name is Amelia Mignonette Grimaldi Thermopolis Renaldo. In the movie, her royal last name is Renaldi.
  6. Mia's friends
    In the books, Mia has a wide and diverse group of girlfriends. In the movie, she just has Lilly.