Answers
Oct 27, 2014 - 02:55 PM
Qu'est-ce que is more formal and polite, whereas quoi is more familiar. It's all a matter of situations. I hope this helps!
Oct 29, 2014 - 02:07 PM
Also, I believe you have to use quoi when it is preceded by a preposition such as "de." For example, if you want to say "What do you(i) need?" it would be "Tu as besoin de quoi?" There is no way to say this with "qu'est-ce que." (I think)