What is the main conflict in The Princess Diaries by Meg Cabot?

The main conflict in the novel, The Princess Diaries, revolves around Mia's attempts to reconcile the two seemingly irreconcilable aspects of her character. Is she plain old Mia Thermopolis from Albert Einstein High, or is she Amelia Mignonette Grimaldi Thermopolis Renaldo, Princess of Genovia?