agenda vs order of business

agenda and order of business both are nouns.

Word	Noun	Adjective	Verb	Adverb
agenda	Yes	No	No	No
order of business	Yes	No	No	No

As nouns, agenda and order of business are synonyms defined as:

agenda and order of business: a list of matters to be taken up (as at a meeting)

Other synonyms of agenda include agendum.

agenda (noun)	order of business (noun)
a temporally organized plan for matters to be attended to	a list of matters to be taken up (as at a meeting)
a list of matters to be taken up (as at a meeting)