GDP is the abbreviation of Gross Domestic Product, and GNP is Gross National Product. Both measure the size and the strength of and economy but they are calculated in a different manner. While GDP means the estimated value of the total worth of the production and the service of a country, within the borders, GNP refers to the estimated value of the total worth of production or service of a country, on its land, or abroad. Both are calculated over the course on one year. GDP is used to see the strength of a country’s local economy, whereas GNP is to see how the nationals of a country are doing economically.