Defense Department vs US Navy

Defense Department and US Navy both are nouns.

Word	Noun	Adjective	Verb	Adverb
Defense Department	Yes	No	No	No
US Navy	Yes	No	No	No

Defense Department (noun)	US Navy (noun)
the federal department responsible for safeguarding national security of the United States; created in 1947	the navy of the United States of America; the agency that maintains and trains and equips combat-ready naval forces