questioning vs quizzical

questioning is a noun but quizzical is not a noun.

Word	Noun	Adjective	Verb	Adverb
questioning	Yes	Yes	No	No
quizzical	No	Yes	No	No

As adjectives, questioning and quizzical are synonyms defined as:

questioning and quizzical: perplexed (as if being expected to know something that you do not know)

questioning (noun)	quizzical (noun)
a request for information

questioning (adjective)	quizzical (adjective)
showing curiosity	perplexed (as if being expected to know something that you do not know)
marked by or given to doubt	playfully vexing (especially by ridicule)
perplexed (as if being expected to know something that you do not know)