What is the difference between KRA ,KPA,KPI?

KPA - Key Performance Area (Ex: Family) ----->  Scope

KRA - Key Result Area (Ex: Family Members)------------> What you are responsible for?

KPI - Key Performance Indicator (Ex: Member's success ) ------> How much is your success rate? 

In simple terms, every individual who are part of a family having the responsibility of contributing to their family. Hence Family is your broader area  (KPA) and in the family every individual having specific responsibility (KRA) and finally how much the person is successful in his role (KPI).