What is the difference between adiós and chau?
Do they both mean "goodbye"?
- I am going now, see you tomorrow, ¡adiós!
- I am going now, see you tomorrow, ¡chau!
Traditionally, adiós is used for someone leaving for an extended period of time or with no expectation of seeing them again.
Chau is informal, and would virtually always imply you'd be expecting to see them again relatively soon.
If you're leaving work and going to meet up with coworkers later for drinks, chau is better than adiós. If you're going abroad and won't see your parents for a year or two, adiós is better. If you go to a store and the worker there didn't expect to see you ever again, they'll probably use adiós, but if it's a corner store and they know, you're more likely to hear chau.
Modern usage may vary some, and different countries may treat them slightly differently (and certainly there dozens more with similar but not exactly the same connotations), but the distinction ought to hold up pretty panhispanicly.