brain stem vs neural structure

brain stem and neural structure both are nouns.

Word	Noun	Adjective	Verb	Adverb
brain stem	Yes	No	No	No
neural structure	Yes	No	No	No

As nouns, neural structure is a hypernym of brain stem; that is, neural structure is a word with a broader meaning than brain stem:

brain stem: the part of the brain continuous with the spinal cord and comprising the medulla oblongata and pons and midbrain and parts of the hypothalamus
neural structure: a structure that is part of the nervous system

brain stem (noun)	neural structure (noun)
the part of the brain continuous with the spinal cord and comprising the medulla oblongata and pons and midbrain and parts of the hypothalamus	a structure that is part of the nervous system