whiten vs bleach

whiten is not a noun while bleach is a noun.

Word	Noun	Adjective	Verb	Adverb
whiten	No	No	Yes	No
bleach	Yes	No	Yes	No

As verbs, bleach is a hyponym of whiten; that is, bleach is a word with a more specific, narrower meaning than whiten:

whiten (noun)	bleach (noun)
	the act of whitening something by bleaching it (exposing it to sunlight or using a chemical bleaching agent)
	the whiteness that results from removing the color from something
	an agent that makes things white or colorless

whiten (verb)	bleach (verb)
turn white	make whiter or lighter
	cause to become white or lighter in color