recollection vs retention

recollection and retention both are nouns.

Word	Noun	Adjective	Verb	Adverb
recollection	Yes	No	No	No
retention	Yes	No	No	No

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

Other hypernyms of recollection include memory, retentiveness, retentivity.

recollection (noun)	retention (noun)
the ability to recall past occurrences	the act of retaining something
the process of remembering (especially the process of recovering information by mental effort)	the power of retaining liquid
something recalled to the mind	the power of retaining and recalling past experience