* Trials are the main game. Some take on gym-like qualities, but are still trials.
* 12 new Alolan forms. Some are a suprising ala Alolan Exeggutor, and won't be mainly Kanto.
* The boxart forms are for Solgaleo/Lunala; each one adds 80 stat points to it's BST like Hoopa Unbound. Solgaleo's new BST is 137/137/127/133/109/117, Lunala's is 137/133/109/137/127/117.
* That white thing is a Necromza form which also gets BST boosts with an added rock typing. It's new BST is 97/107/131/137/119/109.
* Lots of the characters will take on similar roles they did in SM.
* Personal Ultra Spaces are confirmed; the people in Kartana's shown in the trailer are fallers who could not escape and have succumbed to life in Ultra Space.
* The plot is more or less the same as it was in SM but with Necrozma being interjected to help resolve the UB problem.
* Better post way + slightly easier way to level up Pokémon but not too significant.

I should be able to questions relating to USUM, but my details are limited.