Answers Hermione's question about the legend of the Chamber of Secrets
Binns is conspicuously absent from the movie series.
Leader of the group of snatchers who ultimately catch Harry and company
In the book, Scabior was clearly second in command.
Betrays the D.A. to Umbridge
In the film, Cho's betrayal is implied to be the cause of Harry and Cho's breakup, while in the book it is Harry's anger at Marietta (and his defense of Hermione's acne curse on Marietta) that results in their split.
The breed of snake Harry speaks to in Philosopher's (Sorceror's) Stone is from this country
Apparently parseltongue has regional variants as well, as the Brazilian boa refers to Harry as his amigo.
Hid the Half Blood Prince's textbook
This will make an important difference in the second part of the Deathly Hallows movie; how will Harry know where the Diadem of Ravenclaw is located?
Interrupts Harry and Ginny's kiss in the Burrow before the wedding.
Ron's anger in the book is replaced by one of the more amusing scenes in the movie.
Person on whom Umbridge uses Snape's last veritaserum
Probably a lie that it was the last of his veritasserum, and the end result is the same; Snape prevents Umbridge from discovering the whereabouts of Sirius Black.
In Chamber of Secrets, the threatening messages written on the wall are written using what medium?
If it is blood, one wonders where it came from when the victims were merely petrified?
Gives the cursed necklace to Katie Bell
Though Malfoy is ultimately responsible in either case, in the movie Draco is seen surreptitiously slipping into a room in the Three Broomsticks where we are led to believe he performs the deed, while in the book Malfoy is in detention that day and an imperioused Rosmerta gives the necklace to Katie.
Discovers Barty Crouch Sr.'s dead body
In the book, when Harry sees Crouch Sr. he is alive but half-mad. When Harry runs to find Dumbledore to get help, Crouch Jr. finds and kills his father and disposes of the body before Dumbledore shows up.
According to Snape, who or what 'causes devastation with the simplest of spells'?
Both are undoubtedly true!
First person Harry sees die in the series (excluding his mother)
In the books, Harry is unconcious when Quirrell dies. This creates a discontinuity between the books and movies, as witnessing Quirrell die should have enabled Harry to see thestrals beginning in Chamber of Secrets.
Provided Harry Potter with Gillyweed
The impostor Moody intended it to be Neville, but when on the eve of the event Neville had not done so, fake-Moody mentioned the possibility of gillyweed when he knew Dobby would overhear.
remember, book followed by movie!
Trivial musings (some spoilers!)
In Deathly Hallows, person who says Voldemort's name, ultimately leading to the capture of Harry, Hermione, and Ron
Death Eaters also arrive at the Lovegood house in the book; Xenophilius still sells Potter out, he just uses more 'traditional' means.
Along with Harry, Hermione, and Draco, receives detention for Norbert affair
The first of two trips into the forest that Ron undeservingly gets credit for; he also didn't meet Grawp in OOTP.
Dies in the Fiendfyre that destroys the Diadem of Ravenclaw
The actor playing Crabbe, Jamie Waylett, has had legal issues and his part was written out of Deathly Hallows Part 2.
Tells Harry what a Thestral is
While the classic 'you're not going mad, I can see them too' line is in both, Harry learns about Thestrals in his magical creatures class in the book.
Found the Room of Requirement for the D.A.
All of Dobby's parts between Goblet of Fire and Half-Blood Prince are cut from the films; Dobby was added to extra scenes in Deathly Hallows I presumably to reacquaint casual fans to the character, lest Dobby's appearance at Malfoy Manor have too much of a Deus Ex Machina feel.
After the Death Eaters crash Bill and Fleur's wedding, this is where Harry, Hermione, and Ron apparate to
Following the battle with Rowle and Dolohov, Ron showed remarkably more bloodlust in the movie than he did in the book.
Gryffindor Captain when Ron makes first appearance as Gryffindor Keeper
The entire movie series is light on Quiddich as compared to the books; Ron initially makes the team in his fifth year, but there is no Quidditch in the OOTP movie.
Immediately before Riddle gets Hagrid expelled, this is the Hogwarts staff member Riddle speaks with about the possibility of Hogwarts closing.
In the film, it is only mentioned in passing that Armando Dippet is the headmaster responsible for this decision.
Organized the Triwizard Cup
Nearly all of Bagman's role in the text is taken by Crouch in the movie.
Discovers Harry on the Hogwarts Express after being attacked by Malfoy
The books paint most of Luna's beliefs as eccentric to say the least; Luna finding Harry because her spectraspecs allowed her to see wrackspurts is a departure from this tradition.
Introduces Harry to Luna Lovegood
Ginny knows Luna because they are in the same year, though Luna is in Ravenclaw. Luna's house affiliation is left unmentioned in the movies, though it is hinted at that she is Gryffindor. Were she really in Gryffindor, it seems unlikely that Hermione would know Luna though Harry would not.
When Arthur Weasley first meets Harry, this is the Muggle 'technology' that he asks Harry to explain