GDP differs from GNP (Gross National Product) because GDP emphasizes the final goods and services produced within the country at a particular period, while GNP emphasizes the market value of all final goods and services produced by nationals of a country, regardless of their location. In other words, GDP measures the economic output of a country based on the goods and services produced within its borders, while GNP measures the economic output of a country based on the citizenship of the producers.