It's just a downgraded Mickey's Merry Christmas Party. Don't let the After Hours moniker fool you. /s
It sounds pretty similar to AHBB to me.
The attraction overlays will be there all day, it's not like they can flip a switch. They aren't an AH exclusive.
The fireworks could still take place during regular park hours, but would technically fall within that After Hours "early access" time. Again, not an AH exclusive.
It sounds like they're listing things that will be available for day guests and AH guests, just to make it sound more appealing.