doubtfulness vs uncertainty

doubtfulness and uncertainty both are nouns.

Word	Noun	Adjective	Verb	Adverb
doubtfulness	Yes	No	No	No
uncertainty	Yes	No	No	No

As nouns, uncertainty is a hypernym of doubtfulness; that is, uncertainty is a word with a broader meaning than doubtfulness:

doubtfulness: uncertainty about the truth or factuality or existence of something
uncertainty: being unsettled or in doubt or dependent on chance

Other hypernyms of doubtfulness include precariousness, uncertainness.

As nouns, doubtfulness and uncertainty are synonyms defined as:

Other synonyms of doubtfulness include doubt, dubiety, dubiousness, incertitude.

doubtfulness (noun)	uncertainty (noun)
uncertainty about the truth or factuality or existence of something	being unsettled or in doubt or dependent on chance
the state of being unsure of something	the state of being unsure of something