"Usefulness" and "utility" both mean nearly the same thing.
Usefulness: the quality or fact of being useful.
Utility: the state of being useful, profitable, or beneficial
To me, the word "usefulness" sounds rather awkward and could raise doubt among some people as to if it's even a word (although it is). On the other hand, "utility" kind of has the connotations of something like a utilities service or a software utility. Of course it would make sense to reword a sentence when it sounds odd, but this questions serves a purpose when one of these two words must be used.
Is one "better" to use than the other? What is the difference between the two words? When should each be used?
Best Answer
To add to what others have said about the connotations -
I would say that:
Utility sometimes speaks more to how something is used and what makes it useful. The utility of a swiss-army knife can refer to what you can do with it, and perhaps even how.
Usefulness sometimes speaks more to whether and how much something is useful. In the wilderness, the usefulness of a swiss-army knife is generally greater than that of a clipboard.