U. S. Army vs Department of Defense

U. S. Army and Department of Defense both are nouns.

Word	Noun	Adjective	Verb	Adverb
U. S. Army	Yes	No	No	No
Department of Defense	Yes	No	No	No

U. S. Army (noun)	Department of Defense (noun)
the army of the United States of America; the agency that organizes and trains soldiers for land warfare	the federal department responsible for safeguarding national security of the United States; created in 1947