In Arabic, it is Rassoul, the conveyor of the messages of Allah; an Angel.
Angel is fundamentally a Christian term, applied to a man who is sent by God. It is based upon theHebrew Bible which had several stories regarding God's messengers - in the form of human beings - manifesting themselves to Abraham for example.
At least four of the most important verses of the Quran reiterate that Muhammad was ONLY a messenger of Allah.
That he was not creating a new religion but was passing on the Abrahamic religious practices (Rituals) which existed before Muhammad and his Quran.
That Muhammad's sole role was to deliver the Quran, the message of the One and Only Allah which the pagan Arabs had allegedly forgotten.
3:81Behold! Allah took the covenant of the Prophets [Nabiyeen] saying: "I give you a Book and Wisdom; then comes to you an Messenger [Rassoul] confirming what is with you; do ye believe him and render him help." Allah said: "Do ye agree and take this My Covenant as binding on you?" They said: "We agree." He said: "Then bear witness and I am with you among the witnesses"
*** It is very clear from the verse above that according to the Quran, a Prophet is given Scripture and Wisdom while a Messenger would come only to Confirm existing Scriptures ***
5:99 " The messenger[al rassoul] has no function EXCEPT delivering the message (Quran)…";
13:40 " ….your ONLY mission (O Muhammad) is to deliver (Quran),while it is we who will call them to account"
16:123 " Then we inspired you (O Muhammad) to follow the religion of Abraham, monotheism; never was he an idol worshipper"
22:52 Never did We send an messenger [rassooli] or a prophet [nabi] before thee but when he framed a desire Satan threw some (vanity) into his desire: but Allah will cancel anything (vain) that Satan throws in and Allah will confirm (and establish) His Signs: for Allah is full of knowledge and wisdom
42:48 " ….you (O Muhammad) have no duty EXCEPT delivering the message (Quran)"
*** The above verses make it crystal clear that there is a definite distinction between a Prophet and Messenger ***
The pagan Arabs and the idolators of Quraysh used to observe prayers [salat] as shown in-
8:34-35 "…Their prayer [salatuhum] at the House (Ka'aba) were nothing more than deceit and repulsion…".
A fewweeks after this revelation, the following was commanded in the Quran-
73:20 " ….and observe regular prayers [salawat] and give regular charity [zakat], and lend Allah a loan of righteousness. Whatever you advance for your souls, you will find it in Allah's presence better and multiplied manifold…"
*** These verses can only make sense if the listeners, the Arabs (pagan or 'Muslim'), were already practicing these deeds.
A Messenger(Rassoul) is commissioned by Allah to confirm EXSTINGScripture while a Prophet (Nabi) is a messenger of God who delivers NEW Scripture.
AllProphets are Messengers but not all Messengers are Prophets.
Muhammad does not create a NEW RELIGION in his Quran. He only CONFIRMS previous revelations.