staff office vs department

staff office and department both are nouns.

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

As nouns, department is a hypernym of staff office; that is, department is a word with a broader meaning than staff office:

staff office: the department responsible for hiring and training and placing employees and for setting policies for personnel management
department: a specialized division of a large organization

Other hypernyms of staff office include section.

staff office (noun)	department (noun)
the department responsible for hiring and training and placing employees and for setting policies for personnel management	a specialized sphere of knowledge
	a specialized division of a large organization
	the territorial and administrative division of some countries (such as France)