practicality vs usefulness

practicality and usefulness both are nouns.

Word	Noun	Adjective	Verb	Adverb
practicality	Yes	No	No	No
usefulness	Yes	No	No	No

As nouns, usefulness is a hypernym of practicality; that is, usefulness is a word with a broader meaning than practicality:

practicality: concerned with actual use rather than theoretical possibilities
usefulness: the quality of being of practical use

Other hypernyms of practicality include utility.

practicality (noun)	usefulness (noun)
concerned with actual use rather than theoretical possibilities	the quality of being of practical use