regression vs defense mechanism

regression and defense mechanism both are nouns.

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

As nouns, defense mechanism is a hypernym of regression; that is, defense mechanism 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 mechanism: (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 reaction.

regression (noun)	defense mechanism (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