National income (NI) is the sum of income earned by the factors of production owned by a country's citizens. It includes wages, salaries, and fringe benefits paid for labor services, rent paid for the use of land and buildings, interest paid for the use of money, and profits received for the use of capital resources. It is basically the same as GDP.
Micro-economic definition: Personal income (PI), is the money income received by households and individuals before personal income taxes are subtracted, and disposable income (DI) is personal income less personal income taxes.
Macro-economic definition: Personal income in the aggregate of all individuals typically resolves itself in a non-recessionary year around 92%-94% of GDP annually, the remainder of GDP being infrastructure improvements, buildings, inventories, etc. In the macro-economic definition of personal income, taxes are included. Its technical term is Personal consumption expenditure (PCE).