aculeus vs spine

aculeus and spine both are nouns.

Word	Noun	Adjective	Verb	Adverb
aculeus	Yes	No	No	No
spine	Yes	No	No	No

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

Other hyponyms of aculeus include pricker, prickle, spikelet, sticker, thorn.

aculeus (noun)	spine (noun)
a sharp-pointed process especially a sting of a hymenopterous insect	a sharp rigid animal process or appendage; as a porcupine quill or a ridge on a bone or a ray of a fish fin
a stiff sharp-pointed plant process	the part of a book's cover that encloses the inner side of the book's pages and that faces outward when the book is shelved
	the series of vertebrae forming the axis of the skeleton and protecting the spinal cord
	a small sharp-pointed tip resembling a spike on a stem or leaf
	any sharply pointed projection