Firstly, gone are the delicate ballet shoes and uncomfortable corsets. Watson said she felt like Belle is an "active" princess and therefore she'll be wearing a much more practical pair of boots throughout the film. The iconic yellow dress is also be corset-free. Belle has an updated wardrobe.
"For Emma, it was important that the dress was light and that it had a lot of movement," costume designer Jacqueline Durran told EW. "In Emma's reinterpretation, Belle is an active princess. She did not want a dress that was corseted or that would impede her in any way."
In the trailer we also see Belle jailed, whereas in the original she was put into a bedroom where she remained the Beast's captive. In this version we see Belle in a jail cell at the top of a tower.
While there are a few subtle difference, the trailer stays fairly true to the original, so much so that the folks over at Movie Plot cut the two versions together so you can see the similarities.