bodily cavity vs body structure

bodily cavity and body structure both are nouns.

Word	Noun	Adjective	Verb	Adverb
bodily cavity	Yes	No	No	No
body structure	Yes	No	No	No

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

bodily cavity: (anatomy) a natural hollow or sinus within the body
body structure: a particular complex anatomical part of a living thing and its construction and arrangement

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

bodily cavity (noun)	body structure (noun)
(anatomy) a natural hollow or sinus within the body	a particular complex anatomical part of a living thing and its construction and arrangement