denial vs defense reaction

denial and defense reaction both are nouns.

Word	Noun	Adjective	Verb	Adverb
denial	Yes	No	No	No
defense reaction	Yes	No	No	No

As nouns, defense reaction is a hypernym of denial; that is, defense reaction is a word with a broader meaning than denial:

denial: (psychiatry) a defense mechanism that denies painful thoughts
defense reaction: (psychiatry) an unconscious process that tries to reduce the anxiety associated with instinctive desires

Other hypernyms of denial include defence, defence mechanism, defence reaction, defense, defense mechanism.

denial (noun)	defense reaction (noun)
a defendant's answer or plea denying the truth of the charges against him	(psychiatry) an unconscious process that tries to reduce the anxiety associated with instinctive desires
renunciation of your own interests in favor of the interests of others
the act of refusing to comply (as with a request)
the act of asserting that something alleged is not true
(psychiatry) a defense mechanism that denies painful thoughts