regression vs defense reaction

regression and defense reaction both are nouns.

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

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

regression: (psychiatry) a defense mechanism in which you flee from reality by assuming a more infantile state
defense reaction: (psychiatry) an unconscious process that tries to reduce the anxiety associated with instinctive desires

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

regression (noun)	defense reaction (noun)
returning to a former state	(psychiatry) an unconscious process that tries to reduce the anxiety associated with instinctive desires
the relation between selected values of x and observed values of y (from which the most probable value of y can be predicted for any value of x)
(psychiatry) a defense mechanism in which you flee from reality by assuming a more infantile state
an abnormal state in which development has stopped prematurely