In a surprise announcement, the hit game on Wii U will be coming to Nintendo's portable device... with a few downgrades.
The big changes from Wii U to 3DS aren't plentiful, and only one would really impact your experience. In the 3DS version, you will not be able to search for a stage by course ID, like you can in the console version. No explanation was given why you can't but you will still be able to find courses in the "100 Mario Challenge" and "Recommended Courses."
Also, the Mystery Mushroom power up will not be available in the portable version as it is an item exclusive to the Wii U. In conjunction with that, some stages made on Wii U will not be playable on 3DS. It may be due to the Mystery Mushroom being removed, or another reason entirely, Nintendo didn't clarify.
Super Mario Maker for 3DS will release on December 2, 2016.
(Source: Kotaku Youtube)