pollster vs questioner

pollster and questioner both are nouns.

Word	Noun	Adjective	Verb	Adverb
pollster	Yes	No	No	No
questioner	Yes	No	No	No

As nouns, questioner is a hypernym of pollster; that is, questioner is a word with a broader meaning than pollster:

Other hypernyms of pollster include asker, enquirer, inquirer, querier.

pollster (noun)	questioner (noun)
someone who conducts surveys of public opinion	someone who asks a question