effortfulness vs difficulty

effortfulness and difficulty both are nouns.

Word	Noun	Adjective	Verb	Adverb
effortfulness	Yes	No	No	No
difficulty	Yes	No	No	No

As nouns, difficulty is a hypernym of effortfulness; that is, difficulty is a word with a broader meaning than effortfulness:

effortfulness: the quality of requiring deliberate effort
difficulty: the quality of being almost beyond one's ability to deal with and requiring a great effort to achieve a positive result

Other hypernyms of effortfulness include difficultness.

effortfulness (noun)	difficulty (noun)
the quality of requiring deliberate effort	an effort that is inconvenient
	the quality of being almost beyond one's ability to deal with and requiring a great effort to achieve a positive result