Little Nemo

Both involve the main character being whisked away into another world where they meet other people. Both include kings that rule the land they're taken to, royal advisers, and mischievous characters of some-sort (and crows lol). Both have the main character face some difficult situation that they resolve with the help of friends. 

Both movies are silly adventures about naives main protagonists solving absolutely everything with magic in their dreamlands. 

both are about boys who are taken to another world. One based on dreams and the other based on cats. The plots play out a bit differently but they felt extremely similar to me. 

A lot of the staff overlaps, and it's another good, if dark, children's movie. 

I heard that Spirited Away was inspired from Little Nemo. Also the main characters and stories have slight similarities (except that Nemo being a boy and Chihiro being a girl) and are both very enjoyable. 

movies about creative boys, and has that feel of an old dream through elements like flight, trains, magic, science.