archangel vs Angelica Archangelica

archangel and Angelica Archangelica both are nouns.

Word	Noun	Adjective	Verb	Adverb
archangel	Yes	No	No	No
Angelica Archangelica	Yes	No	No	No

As nouns, archangel and Angelica Archangelica are synonyms defined as:

archangel and Angelica Archangelica: a biennial cultivated herb; its stems are candied and eaten and its roots are used medicinally

Other synonyms of archangel include garden angelica.

archangel (noun)	Angelica Archangelica (noun)
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
a biennial cultivated herb; its stems are candied and eaten and its roots are used medicinally