The Incredible Journey/Homeward Bound
Homeward Bound was a notable movie in my childhood, one I can recall watching on multiple occasions and I was surprised to find I still enjoy now. It wasn't until I became a librarian that I realized that it was based on a book. There are a number of similarities between the two and a few notable differences. Many of the major plot points from Burnford's novel are played out on screen (or if not the exact plot elements, something similar enough to recognized it's origin). One could say that the heart of these two stories remains the same. The book, though, is largely a drama, a survival tale. It chronicles the drive of a group of animals to find home, the ways that they take care of each other and the lengths that they will go to in order to survive. The movie, on the other hand, is a family comedy. The adventure/survival elements are still present, they're just tempered by humor. The movie gives the animals voices and alters their personalities, creating interpersonal conflict to amp up the drama. To my mind, though, both of these stories are worth experiencing.
In my research, I discovered that this is the second version of The Incredible Journey that Disney has made. I wasn't able to get a copy of the 1967 version. If anyone has seen it, I'd love to hear what you thought of it and how it compares to the original book.