Internal Revenue Service vs Treasury Department

Internal Revenue Service and Treasury Department both are nouns.

Word	Noun	Adjective	Verb	Adverb
Internal Revenue Service	Yes	No	No	No
Treasury Department	Yes	No	No	No

Internal Revenue Service (noun)	Treasury Department (noun)
the bureau of the Treasury Department responsible for tax collections	the federal department that collects revenue and administers federal finances; the Treasury Department was created in 1789