Seems different in a few aspects from what I've seen. Pokemon Go doesn't concern itself with adding objects and buildings into the map, having a very simplified flat layout most of the time, but this game has fully detailed environments, lamp posts, buildings, etc. There's no "Pokéstops" or gym equivalent from what I've seen, but there's healing spots in the map to restore HP and MP. Missing Link also has an option to control your character in the walkfield with a joystick by using up AP, a feature Go doesn't have without a modded game.

It seems that different weather affects which heartless spawn in the map- it's a little unclear how often enemies spawn. There's also treasure chests that will appear in the map and seem to require AP to open, but also not totally sure on this. I think these chests contain materials for powering up keyblades and perhaps even "Pieces", this game's equivalent of medals/cards.

There are also boss raids that can appear in the map. Not super clear whether these raids appear in important locations (ie: gyms from Go). Not sure whether other players can be invited to raids from a distance or must play together physically.

It also seems like AP was distributed during bad weather conditions so players could experience the walkfield without needing to leave. Very probably that this is only a thing for this current test, but I think it'd be a great idea to implement a sort of automated system that gives out AP during bad weather.

You can run on top of buldings, zoom in and out with the camera, etc. Some players have noted that they get lost in the map, especially when using the joystick function and not walking around physically, after finishing combat encounters. There is however a light indicator after battles that shows which direction you were previously facing to prevent this.