lumbar vein vs vena

lumbar vein and vena both are nouns.

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

As nouns, vena is a hypernym of lumbar vein; that is, vena is a word with a broader meaning than lumbar vein:

lumbar vein: veins that drain the posterior body wall and the lumbar vertebral venous plexuses
vena: a blood vessel that carries blood from the capillaries toward the heart

Other hypernyms of lumbar vein include vein, venous blood vessel.

lumbar vein (noun)	vena (noun)
veins that drain the posterior body wall and the lumbar vertebral venous plexuses	a blood vessel that carries blood from the capillaries toward the heart