insignia vs caduceus

insignia and caduceus both are nouns.

Word	Noun	Adjective	Verb	Adverb
insignia	Yes	No	No	No
caduceus	Yes	No	No	No

As nouns, caduceus is a hyponym of insignia; that is, caduceus is a word with a more specific, narrower meaning than insignia:

insignia: a badge worn to show official position
caduceus: an insignia used by the medical profession; modeled after the staff of Hermes

Other hyponyms of insignia include insignia of rank, shoulder flash, hash mark, hashmark, service stripe, cordon, wings.

insignia (noun)	caduceus (noun)
a badge worn to show official position	an insignia used by the medical profession; modeled after the staff of Hermes