Differences between manga and movie?
Are there any to speak of?
J.
After 18 months of giving this question due thought, there is one humongous difference between the film and the manga. Otherwise, it's pretty accurate adaptation. Don't read beyond this if you do not want to be disappointed or distressed.
In the Manga, Yuki was originally Haru's cat. When Haru finally recognizes Yuki, she hugs her and says, "I thought you had died." The next pane shows Yuki, out of Haru's view, appear suddenly sad. Hence, in the manga, the "cat kingdom" is revealed at that time as a cat heaven.