corp vs business firm

corp and business firm both are nouns.

Word	Noun	Adjective	Verb	Adverb
corp	Yes	No	No	No
business firm	Yes	No	No	No

As nouns, business firm is a hypernym of corp; that is, business firm is a word with a broader meaning than corp:

corp: a business firm whose articles of incorporation have been approved in some state
business firm: the members of a business organization that owns or operates one or more establishments

Other hypernyms of corp include firm, house.

corp (noun)	business firm (noun)
a business firm whose articles of incorporation have been approved in some state	the members of a business organization that owns or operates one or more establishments