Sylvian aqueduct vs duct

Sylvian aqueduct and duct both are nouns.

Word	Noun	Adjective	Verb	Adverb
Sylvian aqueduct	Yes	No	No	No
duct	Yes	No	No	No

As nouns, duct is a hypernym of Sylvian aqueduct; that is, duct is a word with a broader meaning than Sylvian aqueduct:

Sylvian aqueduct: a canal connecting the third and fourth ventricles
duct: a bodily passage or tube lined with epithelial cells and conveying a secretion or other substance

Other hypernyms of Sylvian aqueduct include canal, channel, epithelial duct.

Sylvian aqueduct (noun)	duct (noun)
a canal connecting the third and fourth ventricles	an enclosed conduit for a fluid
	a bodily passage or tube lined with epithelial cells and conveying a secretion or other substance
	a continuous tube formed by a row of elongated cells lacking intervening end walls