regression vs defence mechanism

regression and defence mechanism both are nouns.

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

As nouns, defence mechanism is a hypernym of regression; that is, defence 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
defence mechanism: (psychiatry) an unconscious process that tries to reduce the anxiety associated with instinctive desires

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

regression (noun)	defence 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