ما الفرق بين الرسول والنبي؟

The difference between a Prophet (Nabi) and a Messenger (Rasul) lies in their generality and specificity. A Prophet is more general, while a Messenger is more specific. A Prophet is anyone to whom Allah the Almighty has revealed, whether he was commanded to convey the message or not. If he was not commanded to convey it, then he is a Prophet but not a Messenger. If he was commanded to convey it, then he is both a Prophet and a Messenger.