Defense Department vs United States Department of Defense

Defense Department and United States Department of Defense both are nouns.

Word	Noun	Adjective	Verb	Adverb
Defense Department	Yes	No	No	No
United States Department of Defense	Yes	No	No	No

As nouns, Defense Department and United States Department of Defense are synonyms defined as:

Defense Department and United States Department of Defense: the federal department responsible for safeguarding national security of the United States; created in 1947

Other synonyms of Defense Department include Defense, Department of Defense, DoD.

Defense Department (noun)	United States Department of Defense (noun)
the federal department responsible for safeguarding national security of the United States; created in 1947	the federal department responsible for safeguarding national security of the United States; created in 1947