selection vs mixture

selection and mixture both are nouns.

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

As nouns, mixture is a hypernym of selection; that is, mixture is a word with a broader meaning than selection:

selection (noun)	mixture (noun)
the act of choosing or selecting	the act of mixing together
the person or thing chosen or selected	an event that combines things in a mixture
a passage selected from a larger work	any foodstuff made by combining different ingredients
an assortment of things from which a choice can be made	a collection containing a variety of sorts of things
a natural process resulting in the evolution of organisms best adapted to the environment	(chemistry) a substance consisting of two or more substances mixed together (not in fixed proportions and not with chemical bonding)