The demo is currently out for Nintendo 3DS at the North America eShop. There are 2 short game modes available with 2 team choices each; one introduction mode (presumedly easy mode) and an expert mode. Both modes start off with an explanation on how to play and it is worth going through again as there are some new gameplay stuff and controls compared to the mobile version.
The biggest difference is the Mario theme, being able to use a stylus, if you don't already use it on the phone version, and 3D stereoscopic graphics. The time limit to move the orbs seem shorter but it is probably due to me getting use to the time increase awakenings on my teams on the mobile version.
I was looking forward to the game but after trying out, I kinda lost interest as it is pretty much the same game as the mobile version of Puzzle and Dragons. I thought there will be a difference with using the stylus and there sure is, as you do not get your finger blocking the view but I'm used to using my fingers to move orbs. The iPhone retina graphic is also noticeably better although the 3DS version has animated enemies.
I was hoping for a collaboration dungeon or rare egg machine for the mobile game but since the Japan version was already out on 29 April 2015 and there wasn't any news or announcement of Mario characters, I guess there won't be any. There is a lot of time invested in the mobile version as well as the daily playing involved for me so I do not see myself picking up this 3DS version at all. On the other hand, it is definitely something for non-PAD players to check out, especially puzzle game lovers.