iliac vein vs vena

iliac vein and vena both are nouns.

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

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

iliac vein: one of three veins draining the pelvic area
vena: a blood vessel that carries blood from the capillaries toward the heart

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

iliac vein (noun)	vena (noun)
one of three veins draining the pelvic area	a blood vessel that carries blood from the capillaries toward the heart