headquarters vs central office

headquarters and central office both are nouns.

Word	Noun	Adjective	Verb	Adverb
headquarters	Yes	No	No	No
central office	Yes	No	No	No

As nouns, headquarters and central office are synonyms defined as:

headquarters and central office: (usually plural) the office that serves as the administrative center of an enterprise

Other synonyms of headquarters include home base, home office, main office.

headquarters (noun)	central office (noun)
the military installation from which a commander performs the functions of command	(usually plural) the office that serves as the administrative center of an enterprise
(usually plural) the office that serves as the administrative center of an enterprise
(plural) a military unit consisting of a commander and the headquarters staff