Quite a lot more, I’d say there is 2x to 3x more. And more importantly it feels complete. The movie seems like it needed a sequel and that sequel is in the manga.
If you liked the movie you’ll love the manga, guaranteed
I always loved the movie's art design and sense of place, but the plot felt a little threadbare. Sounds like the manga might be worth a look just to get a fuller picture of the world.