Angels are:
- Attendants to God's throne; Daniel 7:9-10, Psalm 96:7, Psalm 102.20. The six-winged Seraphim who minster at God's throne. Isaiah 6. A special group of 7 angels who's function is to stand before the throne of God; Rev 8:2-5
- God's assistants; Job 1:6, 2:1
These are special glimpses into heaven. Generally, humans interact with angels in their role as messengers, personal guardians, defenders of the faithful, executing miracles while acting as divine agents, representing and in some cases, putting into execution God's will.
To the topic of the OP, there is a hierarchy of angels; ranks in the heavenly army, if you will. Cherubim who are clearly God's ministers. The special group of 7 who surround God's throne. Seraphim. Archangels (1 Thes 4:15). And then St. Paul's description of "principality, and power, and virtue, and dominion" in Ephesians 1:21. And in Col 1:16 where he describes a hierarchy of angels as part of creation. "In Him were all things created in heaven and on earth, visible and invisible, whether thrones or dominations, or principalities or powers."
St Paul also warns of following unlawful angels. First describing them as defeated by Jesus. "and the dominions and powers he robbed of their prey, put them to an open shame, led them away in triumph, through him" (Col 2:15) Followed in verse 18 with an admonition to not worship them.
All in all, there are 9 orders in the host of Heaven. Angels, Archangels, Virtues, Powers, Principalities, Dominations, Throne, Cherubim and Seraphim.