repression vs defence mechanism

repression and defence mechanism both are nouns.

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

As nouns, defence mechanism is a hypernym of repression; that is, defence mechanism is a word with a broader meaning than repression:

repression: (psychiatry) the classical defense mechanism that protects you from impulses or ideas that would cause anxiety by preventing them from becoming conscious
defence mechanism: (psychiatry) an unconscious process that tries to reduce the anxiety associated with instinctive desires

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

repression (noun)	defence mechanism (noun)
the act of repressing; control by holding down	(psychiatry) an unconscious process that tries to reduce the anxiety associated with instinctive desires
(psychiatry) the classical defense mechanism that protects you from impulses or ideas that would cause anxiety by preventing them from becoming conscious
a state of forcible subjugation