vena iliaca vs iliac vein

vena iliaca and iliac vein both are nouns.

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

As nouns, vena iliaca and iliac vein are synonyms defined as:

vena iliaca (noun)	iliac vein (noun)
one of three veins draining the pelvic area	one of three veins draining the pelvic area