naysayer vs resister

naysayer and resister both are nouns.

Word	Noun	Adjective	Verb	Adverb
naysayer	Yes	No	No	No
resister	Yes	No	No	No

As nouns, resister is a hypernym of naysayer; that is, resister is a word with a broader meaning than naysayer:

naysayer: someone with an aggressively negative attitude
resister: someone who systematically obstructs some action that others want to take

Other hypernyms of naysayer include obstructer, obstructionist, obstructor, thwarter.

naysayer (noun)	resister (noun)
someone with an aggressively negative attitude	someone who systematically obstructs some action that others want to take
	someone who offers opposition