retentivity vs mental faculty

retentivity and mental faculty both are nouns.

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

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

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

Other hypernyms of retentivity include faculty, module.

retentivity (noun)	mental faculty (noun)
the power of retaining liquid	one of the inherent cognitive or perceptual powers of the mind
the property of retaining possessions that have been acquired
the power of retaining and recalling past experience