naysayer vs obstructor

naysayer and obstructor both are nouns.

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

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

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

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

naysayer (noun)	obstructor (noun)
someone with an aggressively negative attitude	any structure that makes progress difficult
	someone who systematically obstructs some action that others want to take