This is the biggest reason I'm glad I held off on vanilla S/M myself. Once you go black in XY, you don't go back.

You can be black in Sun/Moon.

You were locked to the default mains in ORAS, with zero customization options. I was told that you couldn't change your skin tone in SM, but I've been corrected by the post above.

Oh, didn't know that. My friend said that you couldn't, so I just took her word for it, even though I thought it would be a very odd thing to take away after XY.

-More customization options for your character avatar

-New Lycanroc form that we knew about weeks ago (but confirmed to definitely have Tough Claws, and gets both exclusive moves from the other two forms)

-The video LOOKS like it had a Rockruff following the main character around for a second, but it was probably intentionally misleading. It was only for a couple of seconds, and there was no text confirming that the feature of Pokemon following you in the overworld would be returning. It could have  been an NPC Rockruff.

-"More secrets of the Alola region to be revealed!"

-A couple of minor characters from the first SM seem to have bigger roles, like Ryuki and this chick whose name I can't remember.

I don't know if no one has noticed yet or just not mentioning it, but there is an eye in the white light of each of the box arts which is interesting.

Edit:

They combine together to make that wierd thing in the middle.

Looks like Deoxys... who is from space.

I wonder what is that huge black hole above one of the islands. Maybe it'll transport you to an alternate dimension or something