persecutor vs pest

persecutor and pest both are nouns.

Word	Noun	Adjective	Verb	Adverb
persecutor	Yes	No	No	No
pest	Yes	No	No	No

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

Other hyponyms of persecutor include harasser, blighter, cuss, gadfly, pesterer, tantaliser, tantalizer, witch-hunter.

persecutor (noun)	pest (noun)
someone who torments	any unwanted and destructive insect or other animal that attacks food or crops or livestock etc.
	a persistently annoying person
	any epidemic disease with a high death rate
	a serious (sometimes fatal) infection of rodents caused by Yersinia pestis and accidentally transmitted to humans by the bite of a flea that has bitten an infected animal