ductulus vs sweat duct

ductulus and sweat duct both are nouns.

Word	Noun	Adjective	Verb	Adverb
ductulus	Yes	No	No	No
sweat duct	Yes	No	No	No

As nouns, sweat duct is a hyponym of ductulus; that is, sweat duct is a word with a more specific, narrower meaning than ductulus:

ductulus: a very small duct
sweat duct: a small duct that conveys sweat from a sudoriferous gland to the surface of the skin

Other hyponyms of ductulus include biliary ductule.

ductulus (noun)	sweat duct (noun)
a very small duct	a small duct that conveys sweat from a sudoriferous gland to the surface of the skin