hemizygos vein vs vena hemizygos

hemizygos vein and vena hemizygos both are nouns.

Word	Noun	Adjective	Verb	Adverb
hemizygos vein	Yes	No	No	No
vena hemizygos	Yes	No	No	No

As nouns, hemizygos vein and vena hemizygos are synonyms defined as:

hemizygos vein and vena hemizygos: a continuation of the left ascending lumbar vein; crosses the midline at the 8th vertebra and empties into the azygos vein

Other synonyms of hemizygos vein include hemizygous vein.

hemizygos vein (noun)	vena hemizygos (noun)
a continuation of the left ascending lumbar vein; crosses the midline at the 8th vertebra and empties into the azygos vein	a continuation of the left ascending lumbar vein; crosses the midline at the 8th vertebra and empties into the azygos vein