aorta vs thoracic aorta

aorta and thoracic aorta both are nouns.

Word	Noun	Adjective	Verb	Adverb
aorta	Yes	No	No	No
thoracic aorta	Yes	No	No	No

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

aorta: the large trunk artery that carries blood from the left ventricle of the heart to branch arteries
thoracic aorta: a branch of the descending aorta; divides into the iliac arteries

Other hyponyms of aorta include ascending aorta, aortic arch, descending aorta, abdominal aorta.

aorta (noun)	thoracic aorta (noun)
the large trunk artery that carries blood from the left ventricle of the heart to branch arteries	a branch of the descending aorta; divides into the iliac arteries