Michael vs archangel

Michael and archangel both are nouns.

Word	Noun	Adjective	Verb	Adverb
Michael	Yes	No	No	No
archangel	Yes	No	No	No

As nouns, archangel is a hypernym of Michael; that is, archangel is a word with a broader meaning than Michael:

Michael: (Old Testament) the guardian archangel of the Jews
archangel: an angel ranked above the highest rank in the celestial hierarchy

Michael (noun)	archangel (noun)
(Old Testament) the guardian archangel of the Jews	an angel ranked above the highest rank in the celestial hierarchy
	a biennial cultivated herb; its stems are candied and eaten and its roots are used medicinally