Both my friend and I work in same place. What can I say when, at end of the day, we are leaving the office? Is it either "Auf Wiedersehen" or "Tschüss? He is my colleague and friend.
You generally can't do much wrong if you choose between "Auf Wiedersehen" or "Tschüss" corresponding to how you did greet someone:
- "Hallo" <-> "Tschüss" (rather informal - looks to be the better choice here since you called him "a friend")
- "Guten Tag/Morgen" <-> "Auf Wiedersehen" (rather formal)
There's also the option to say "Bis morgen!" (Mon-Thu) / "Bis nächsten Montag!" (Fri), which pretty much works in any setting (except maybe super formal).
Both are common phrases used when leaving someone after a meeting or any other everyday situation.
is the more polite and formal way of saying this.
should be reserved for friends, relatives and close colleagues.
It would be impolite to use Tschüss for people you do not know very well, or for superiors at your work place. Likewise it would be a little bit awkward to use Auf Wiedersehen for your close friends. You may however well use Auf Wiedersehen when you were at dinner at your neighbours to whom you have a friendly but not too close relationship.
When leaving a shop where you bought something it is advisable to say Auf Wiedersehen, although you may hear people saying Tschüss, too.