That’s a great question — and it’s wonderful to see you paying such close attention to these small but important distinctions!
You’re right that quelque chose and autre chose can sound similar, but they’re used in slightly different contexts:
quelque chose means something or anything.
Example: Vous voulez boire quelque chose ? → “Would you like to drink something?”
This is used when offering or asking if someone wants anything at all.
autre chose means something else.
Example: Autre chose ? → “Anything else?”
This is used when you’ve already mentioned or ordered something, and you’re asking if the person wants something in addition.
So in your examples:
The waiter saying “Autre chose ?” comes after you’ve already ordered something.
The phrase “Vous voulez boire quelque chose ?” is a general offer, not a follow-up.
That’s why they’re not interchangeable — quelque chose introduces something new, while autre chose refers to an additional thing.
Hope this clears it up! You’re doing great — it’s details like this that make a big difference as you move forward in Level 2.
Best regards,