naysayer vs obstructer

naysayer and obstructer both are nouns.

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

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

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

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

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