In essence the 2016 film The BFG is very similar to the book. In both there is a young called Sophie who is taken by the BFG (also known as the Big Friendly Giant) to Giant country because he fears that she will tell the public that giants are real. The two become friends and plot a way to stop the other giants from eating children, their favourite and seemingly only pastime. They agree that they are not in a position to carry out such an ambitious plan so they go to the Queen of England for help. Between them they successfully trap the giants, condemning them to a life of eating snozzcumbers. That is where the similarities stop.
One of the most notable differences is in the respective endings. The book shows Sophie living in the grounds of the royal palace with the BFG, teaching him to read whilst he writes a book about his life. In the film Steven Spielberg takes artistic license by editing this ending, instead electing to have Sophie living happily in the castle whilst the BFG lives in solitude in Giant Country. This minor difference creates a massive divide between the book and the film. Simply put, the book accepts giants as being real and the film only sees them as being a possibility. With the BFG living in an unpotable country and the other giants living on an equally unpotable island the film does not outright reject their existence but it places them in a neat little box labelled ‘maybe’.
That being said they both perfectly encapsulate the magic that Roald Dahl is so well known for. The beauty and mystic of the dreams is not lost in the film version but instead enhanced. The myriad of colours brings a new dimension to the concept and is entirely captivating to watch. 12-year-old Ruby Barnhill does justice to young Sophie, perfectly capturing the strength and wonder of the little girl from the book and reflecting that on the screen.
Back to the question: is the book or the film better? Perhaps better is the wrong word because they are both brilliant in their own right. However, if I could only have one, I would still pick the book because it sustains the wonder and magic until the final word.