selection vs volition

selection and volition both are nouns.

Word	Noun	Adjective	Verb	Adverb
selection	Yes	No	No	No
volition	Yes	No	No	No

As nouns, volition is a hyponym of selection; that is, volition is a word with a more specific, narrower meaning than selection:

selection (noun)	volition (noun)
the act of choosing or selecting	the act of making a choice
the person or thing chosen or selected	the capability of conscious choice and decision and intention
a passage selected from a larger work
an assortment of things from which a choice can be made
a natural process resulting in the evolution of organisms best adapted to the environment