USA vs Defense Department

USA and Defense Department both are nouns.

Word	Noun	Adjective	Verb	Adverb
USA	Yes	No	No	No
Defense Department	Yes	No	No	No

USA (noun)	Defense Department (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
North American republic containing 50 states - 48 conterminous states in North America plus Alaska in northwest North America and the Hawaiian Islands in the Pacific Ocean; achieved independence in 1776