retention vs mental faculty

retention and mental faculty both are nouns.

Word	Noun	Adjective	Verb	Adverb
retention	Yes	No	No	No
mental faculty	Yes	No	No	No

As nouns, mental faculty is a hypernym of retention; that is, mental faculty is a word with a broader meaning than retention:

retention: the power of retaining and recalling past experience
mental faculty: one of the inherent cognitive or perceptual powers of the mind

Other hypernyms of retention include faculty, module.

retention (noun)	mental faculty (noun)
the act of retaining something	one of the inherent cognitive or perceptual powers of the mind
the power of retaining liquid
the power of retaining and recalling past experience