When Fleur Delacour married William Weasley on August 1, 1997, according to the canonical text, she wore a simple white dress and an heirloom tiara. For the movie adaptation, the dress was considerably sexed up.
On your left, above, we have Clémence Poésy, who plays Fleur, embracing Domhnall Gleeson, who plays the eldest Weasley sibling. On your right, we have a dress from Alexander McQueen's fall, 2008, collection. Hmmmmm.
Costume designer Jany Temime, who has worked on five of the Harry Potter movies, told the Los Angeles Times:
For the wedding dress, I wanted it to be a witch wedding dress but not a Halloween dress. The dress is white but it needed to have something fantastic to it. So there is the phoenix [motif], the bird, which is a symbol of love in a way because there is rebirth, love never dies, it is born again. So we have that in front of the dress to give a feeling of eternal love. It was the symbol of Dumbledore, too, but it is the symbol of love for the dress.
See? Totally different. McQueen's dress has kissing peacocks, while Temime's design has kissing phoenixes. Temime says when she was getting inspired to work on the film, she
sharpened her pencil and browsed over to Style.com "looked at extreme cultures, or the fringe, or the outsiders. Any parallel society, like the gypsies or political groups on the edge."