GDI and GDP are two slightly different indicators of a country’s economic activity.
GDI calculates what all participants in the economy earn or “receive” (eg wages, profits and taxes). GDP calculates the value of what an economy produces (such as goods, services, and technology).
One of the basic concepts of macroeconomics is that revenue equals expenditure, which means that GNI will be the same as GDP in an economy in equilibrium.