whitener vs bleaching agent

whitener and bleaching agent both are nouns.

Word	Noun	Adjective	Verb	Adverb
whitener	Yes	No	No	No
bleaching agent	Yes	No	No	No

As nouns, whitener and bleaching agent are synonyms defined as:

whitener and bleaching agent: an agent that makes things white or colorless

Other synonyms of whitener include blanching agent, bleach.

whitener (noun)	bleaching agent (noun)
an agent that makes things white or colorless	an agent that makes things white or colorless