what is the difference between utility and usefulness?????

Utility refers to the satisfaction of human wants. However, it may happen that a commodity provide utility (satisfaction) but is not actually useful (infact they may be harmful). For example, commodities such as cigarettes, alcohol, etc. may provide utility to some people but are not useful in the actual sense; as the consumption of such products are harmful. These commodities are said to fetch utility, as they fulfill the satisfaction of their users (smokers, alcoholics). So, from this we can say that usefulness implies utility, but utility need not necessarily implies usefulness.