I want to know the difference between Nabi (Prophet) and Rasul (Messenger).

Praise be to Allah, the Lord of the World; and may His blessings and peace be upon our Prophet Muhammad and upon all his Family and Companions.

According to the majority of Muslim scholars, a Nabi (Prophet (Sallallahu Alaihi wa Sallam)) is one who has received a Shari'a but is not required to convey it.
A Rasul (Messenger) is one who has received a Shari'a and is required to convey it.
It is also said: A Nabi is one who has received a dependent Shari'a, i.e. it is attached to a previous Shari'a.
A Rasul is one who has received an independent Shari'a'.
Allah knows best.