Angels bring the word of God to the prophets or messengers of God.
Angels do not have free will so are pure and sinless and cannot displease God.
"Each person has angels watching before him and behind, watching over him by God's command"
Angel Jibril (Gabriel) was an archangel and a trusted messenger of God. He relayed the Qur'an to Muhammad from God when he was meditating at Mount Hira.
Angel Mika'il (Michael) was an archangel and an angel of mercy. God assigned him to reward righteous people for their good work during their lives and is also responsible for sending rain, thunder and lightning.
Both angels bring spiritual nourishment. Jibril brings it though God's words and Mika'il brings it for the earth and human life through rain.