As most of the literate and cinema-going world now knows, Harry Potter and Hermione Granger are two of the main characters in J.K. Rowling's Harry Potter series of fantasy novels, the first of which is Harry Potter and the Sorcerer's Stone.

As for similarities, Harry Potter and Hermione Granger are both about the same age and become first-year students at Hogwarts School of Witchcraft and Wizardry at the same time. The sorting hat assigns them both to the house of Gryffindor, where they both become best friends with each other and Ronald Weasley after an encounter with a troll during which Harry and Ronald save Hermione. Harry and Hermione go to the same classes, share many adventures, oppose bullies, and fight the evil Lord Voldemort and his minions.

One of the significant differences between Harry and Hermione is that Harry Potter's real parents are a witch and a wizard, whereas Hermione is muggle-born, which means that her parents were normal humans and she is the first witch in their family. Another difference is that Hermione is studious and precocious, able to study hard and learn spells quickly, but Harry has a normal aptitude for academics, sometimes struggling with his lessons. It's often Hermione who has to come up with appropriate potions or spells, as she has read so many books and has an innate understanding of them. Additionally, Harry is an orphan, his parents having been killed by Voldemort, while Hermione's parents are still alive.