diligence vs conscientiousness

diligence and conscientiousness both are nouns.

Word	Noun	Adjective	Verb	Adverb
diligence	Yes	No	No	No
conscientiousness	Yes	No	No	No

As nouns, conscientiousness is a hypernym of diligence; that is, conscientiousness is a word with a broader meaning than diligence:

diligence: conscientiousness in paying proper attention to a task; giving the degree of care required in a given situation
conscientiousness: the trait of being painstaking and careful

Other hypernyms of diligence include painstakingness.

diligence (noun)	conscientiousness (noun)
a diligent effort	the quality of being in accord with the dictates of conscience
persevering determination to perform a task	the trait of being painstaking and careful
conscientiousness in paying proper attention to a task; giving the degree of care required in a given situation