spinal canal vs duct

spinal canal and duct both are nouns.

Word	Noun	Adjective	Verb	Adverb
spinal canal	Yes	No	No	No
duct	Yes	No	No	No

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

spinal canal: the canal in successive vertebrae through which the spinal cord passes
duct: a bodily passage or tube lined with epithelial cells and conveying a secretion or other substance

Other hypernyms of spinal canal include canal, channel, epithelial duct.

spinal canal (noun)	duct (noun)
the canal in successive vertebrae through which the spinal cord passes	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