activator vs sensitiser

activator and sensitiser both are nouns.

Word	Noun	Adjective	Verb	Adverb
activator	Yes	No	No	No
sensitiser	Yes	No	No	No

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

activator: (biology) any agency bringing about activation; a molecule that increases the activity of an enzyme or a protein that increases the production of a gene product in DNA transcription
sensitiser: (chemistry) a substance other than a catalyst that facilitates the start of a catalytic reaction

Other hyponyms of activator include activating agent, accelerator, catalyst, sensitizer.

activator (noun)	sensitiser (noun)
(biology) any agency bringing about activation; a molecule that increases the activity of an enzyme or a protein that increases the production of a gene product in DNA transcription	(chemistry) a substance other than a catalyst that facilitates the start of a catalytic reaction