And We did not send before you any Messenger nor prophet, but when he desired, the Shaitan made a suggestion respecting his desire; but Allah annuls that which the Shaitan casts, then does Allah establish His communications, and Allah is Knowing, Wise,
وَمَا أَرْسَلْنَا مِنْ قَبْلِكَ مِنْ رَسُولٍ وَلَا نَبِيٍّ إِلَّا إِذَا تَمَنَّىٰ أَلْقَى الشَّيْطَانُ فِي أُمْنِيَّتِهِ فَيَنْسَخُ اللَّهُ مَا يُلْقِي الشَّيْطَانُ ثُمَّ يُحْكِمُ اللَّهُ آيَاتِهِ ۗ وَاللَّهُ عَلِيمٌ حَكِيمٌ
According to this verse, there is a difference between Rasool and Nabi. To me Messenger means one with a message, and Nabi is one who receives divine scripture from God to channel to the people. Since the scripture is God's words - it's said in the function that he is the receiver of that revelation.
However, the book itself from God is a message, which would make a Nabi a Messenger. But there can be Messengers from God that don't have a divine scripture and their message is not divine scripture.
So every Nabi would be a Rasool but not every Rasool a Nabi.
The Knower of the unseen! so He does not manifest His secrets to any,
Except to him whom He chooses as a Messenger, for surely He makes a guard to march before him and after him,
This suggests Allah (swt) reveals secrets to Messengers, but if every Nabi was not a Messenger, they would be missing from this category of who God reveals his secrets to which doesn't make sense.
Allah was not going to leave the believers in the state you are in until He distinguishes the vile from the good. Allah would not let you know the unseen (ghayb), but He chooses whom He wills of His messengers. So believe in Allah and His messengers. If you believe and be pious then you will have a great reward. (3.179)
5:67 also suggests the message is not only the Quran but includes the Sunnah.
وَمَا أَرْسَلْنَا مِنْ قَبْلِكَ مِنْ رَسُولٍ وَلَا نَبِيٍّ إِلَّا إِذَا تَمَنَّىٰ أَلْقَى الشَّيْطَانُ فِي أُمْنِيَّتِهِ فَيَنْسَخُ اللَّهُ مَا يُلْقِي الشَّيْطَانُ ثُمَّ يُحْكِمُ اللَّهُ آيَاتِهِ ۗ وَاللَّهُ عَلِيمٌ حَكِيمٌ
According to this verse, there is a difference between Rasool and Nabi. To me Messenger means one with a message, and Nabi is one who receives divine scripture from God to channel to the people. Since the scripture is God's words - it's said in the function that he is the receiver of that revelation.
However, the book itself from God is a message, which would make a Nabi a Messenger. But there can be Messengers from God that don't have a divine scripture and their message is not divine scripture.
So every Nabi would be a Rasool but not every Rasool a Nabi.
The Knower of the unseen! so He does not manifest His secrets to any,
Except to him whom He chooses as a Messenger, for surely He makes a guard to march before him and after him,
This suggests Allah (swt) reveals secrets to Messengers, but if every Nabi was not a Messenger, they would be missing from this category of who God reveals his secrets to which doesn't make sense.
Allah was not going to leave the believers in the state you are in until He distinguishes the vile from the good. Allah would not let you know the unseen (ghayb), but He chooses whom He wills of His messengers. So believe in Allah and His messengers. If you believe and be pious then you will have a great reward. (3.179)
5:67 also suggests the message is not only the Quran but includes the Sunnah.