What is the difference between "vacation" and the "unavailable" setting?
Vacation pauses your timer to help prevent losing games that have already started. The vacation setting is used when you are unable to move for an extended period and you need to pause your games so that you will not lose on time.
The "unavailable" setting prevents you from being challenged or automatically matched to play new games. It prevents other players from sending you game challenges or tournament invitations and can help limit the number of games you have going on at once.