alveolar bed vs body structure

alveolar bed and body structure both are nouns.

Word	Noun	Adjective	Verb	Adverb
alveolar bed	Yes	No	No	No
body structure	Yes	No	No	No

As nouns, body structure is a hypernym of alveolar bed; that is, body structure is a word with a broader meaning than alveolar bed:

alveolar bed: lung tissue densely packed with alveoli
body structure: a particular complex anatomical part of a living thing and its construction and arrangement

Other hypernyms of alveolar bed include anatomical structure, bodily structure, complex body part, structure.

alveolar bed (noun)	body structure (noun)
lung tissue densely packed with alveoli	a particular complex anatomical part of a living thing and its construction and arrangement