We know in past Pokemon games that the color difference between games did nothing more but help to remind you which Pokemon are exclusive to each game. For Pokemon Sun and Moon, however, the games will take place 12 hours apart. This means that Pokemon Sun will take place in the daytime and Moon in the night presumably...or maybe it means it'll be light and dark at different times? They weren't too specific in the trailer. 

What is known is that different events will take place different ways depending on which game you are playing. This means different Pokemon will appear in different scripted events, as well as other things.

In addition to that revelation we learned about a couple new Pokemon, Team Aether who is rival to the previously announced Team Skull, and Ultra Beasts....whatever they are. See them all on display in the trailer below.