bleach vs whitening

bleach and whitening both are nouns.

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

As nouns, whitening is a hypernym of bleach; that is, whitening is a word with a broader meaning than bleach:

bleach: the act of whitening something by bleaching it (exposing it to sunlight or using a chemical bleaching agent)
whitening: changing to a lighter color

Other hypernyms of bleach include lightening.

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

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