Differences between book and film
Spoiler warning: Plot and/or ending details follow.


* In the movie, Langdon received the photograph of Sauniere's corpse after giving a symbology lecture in a university, while he is autographing his books. In the book, he is contacted after he returned to his hotel.
* The movie makes no verbal reference to the Divine Proportion, however, during a sequence in which Langdon cuts his face shaving, the pattern of the blood droplet in the sink vaguely resembles the shape of the Greek letter Phi.
* Sophie found the hidden message in the Mona Lisa written at the bottom right of the painting. In the novel it is scrawled directly across Mona Lisa's face just like the one shown in the earlier trailers of the film.
* In the movie, Langdon deciphered the code "So Dark The Con of Man" hidden in the Mona Lisa a few minutes after they found it; whereas in the book it took more time.
* Bank manager and one-time collaborator André Vernet turns against Langdon and Sophie because he has been waiting 30 years for somebody to return for the contents of the safe, and believes they may have killed a man to access his valuables. In the movie his selfish interests in the contents are insinuated, whereas in the book a fuller explanation is given of his dedication to protect Sauniere's interests as his client.
* In the movie, Fache goes to the hospital to find Vernet and tells him to turn on the homing device, while in the book Vernet does so without telling Fache, so that his bank's reputation is not spoiled.
* No mention is ever made in the movie of the surveillance equipment in the top of the barn at Teabing's manor, nor of the miniature knight in Sauniere's office in which a bug had been placed.
* There is no second cryptex inside the first. The solution to the cryptex (and the mirrored writing found on the panel behind the rose logo on the box) is the same as the second one in the book.
* The role of Opus Dei in the movie is significantly less ominous than their portrayal in the book. In the movie, Aringarosa is a sinister member of a secret council of priests, called the Council of Shadows, dedicated to the destruction of the Sangreal rather than the desperate leader of Opus Dei dealing with an official council of the Vatican. This leaves Silas' role as more of the tormented executor rather that of the blindly faithful servant.
* It is revealed that Bezu Fache is a member of Opus Dei in the movie; not mentioned in the book. He decides to pursue Robert Langdon as he was given a false tip by Bishop Aringarosa whom he trusted.
* Langdon does not carefully hide the cryptex under furniture to prevent Teabing from discovering it prematurely the way he does in the book.
* In the movie Teabing uses sophisticated computer animation to demonstrate codes in Da Vinci's paintings; whereas in the book he merely points at prints.
* The name of Rémy Legaludec, Leigh Teabing's butler, is changed in the film to "Remy Jean" instead of Rémy Legaludec".
* Remy tells Silas that he is The Teacher in the limo, instead of one of his servants. Remy is poisoned by a pier in the Docklands of London instead of in the limo.
* Silas is killed by police-assisted suicide to show his pain beside where he shot Aringarosa. In the book he flees the scene with mortal wounds and dies in a park.
* In the novel, Robert and Sophie go to a library in London to discover the relevance of A. Pope. Whereas in the movie they borrow a cell phone web browser on a city bus after they realize it will take too long to get to the library. Sophie uses feminine attractiveness to borrow the phone [which may introduce a technique not present in the book]. It is almost comical when the passenger selected merely for his cell phone ends up helping by saying something about the search pattern results on his phone like what a professional librarian data-search expert would say.
* In the book, Sophie and Robert find a note at Newton's tomb telling them to go to a chapel in order to save Teabing, and it is at this chapel where they realize Teabing is "the Teacher". In the movie, Teabing reveals his true identity right at the tomb.
* The revelation of the Teacher and the rest of the ending is presented differently. In the movie, Langdon and Sophie discovered the Sangreal documents - and thus the secrets of Sophie's ancestry - hidden beneath the Rosslyn Chapel. However, in the novel Langdon tells Sophie that she is not a descendant of Christ, and Langdon does not discover the location of the Sangreal documents on his own until the epilogue.
* The entrance to the tomb beneath Rosslyn Chapel is easily found in the movie, beneath an obvious symbol of the unified chalice and blade. In the book, no such entrance to the underground chamber exists (the chamber had only been confirmed by sonograms, but Langdon and Sophie never see it) and the chalice/blade symbol is less obvious (the path of footprints worn into the floor).
* In the book, Jacques Sauniere is Sophie's grandfather, and she is reunited with her grandmother, who lives behind the Rosslyn Chapel, and her brother, the docent, at the end, where it is revealed in the narrative that her grandmother and grandfather separated with great difficulty for the mere purpose of changing the family names and protecting the grandchildren in separate families. In the movie, Langdon tells Sophie that he believes that Jacques Sauniere is not her real grandfather. The docent is never announced as Sophie's brother. Instead, a legion of protectors of the holy grail meet Sophie with her grandmother, the rest being left unexplained.
* In the book, Robert and Sophie kiss in the end. In the movie, Sophie "cures" Robert's phobia, and there are other very sublime touching moments between them, barely implying that some relationship could continue, but without ever implying romance.
* In the movie, there are a sequence of dots that appear for only a few frames. These dots are similar to the laser etchings on the key that Langdon and Sophie discover behind the painting.
* In the movie, Langdon counsels Sophie that it may not necessarily be important or right to prove the bloodline; that it will have to be largely her choice, and that it could be a matter of faith and of deciding which set of beliefs to promote; asking if the proof really matters, anyway. In the book, an explanation is given earlier that the "two" versions of history are merely different, not necessarily making one totally correct over the other, an explanation missing from the movie.
* In the move, Sophie tries to walk on water, and jokes about making water into wine, presumably due to having Jesus’ and Mary's miracle-making genes or blood. In the book, there is no such reference.
* In the book, Leigh shows quotes of Leonardo Da Vinci and many books including Holy Blood, Holy Grail.
* In the book, Silas has red eyes and Sophie has green eyes, while in the movie, they have other colors.
* In the book, Teabing puts peanut dust into Remy's cognac in order to poison him, since Remy has an allergy to peanuts. In the film, the method of poisoning is unspecified and Remy's allergy is not mentioned.
* In the book, Langdon is a firm believer in the Grail theory. However, in the film he dismisses most of it as myth and even argues with Teabing about it several times.

Spoilers end here.