vestibular apparatus vs vestibular system

vestibular apparatus and vestibular system both are nouns.

Word	Noun	Adjective	Verb	Adverb
vestibular apparatus	Yes	No	No	No
vestibular system	Yes	No	No	No

As nouns, vestibular apparatus and vestibular system are synonyms defined as:

vestibular apparatus and vestibular system: organs mediating the labyrinthine sense; concerned with equilibrium

vestibular apparatus (noun)	vestibular system (noun)
organs mediating the labyrinthine sense; concerned with equilibrium	organs mediating the labyrinthine sense; concerned with equilibrium