office vs office staff

office and office staff both are nouns.

Word	Noun	Adjective	Verb	Adverb
office	Yes	No	No	No
office staff	Yes	No	No	No

As nouns, office and office staff are synonyms defined as:

office (noun)	office staff (noun)
a religious rite or service prescribed by ecclesiastical authorities	professional or clerical workers in an office
the actions and activities assigned to or required or expected of a person or group
a job in an organization
place of business where professional or clerical duties are performed
professional or clerical workers in an office
an administrative unit of government
(of a government or government official) holding an office means being in power