order of business vs agenda

order of business and agenda both are nouns.

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

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

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

Other synonyms of order of business include agendum.

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