Defense vs Department of Defense

Defense and Department of Defense both are nouns.

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

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

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

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

Defense (noun)	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