DESCRIPTION
Green beans are the unripe, young fruit of various cultivars of the common bean (Phaseolus vulgaris). Immature or young pods of the runner bean (Phaseolus coccineus), yardlong bean (Vigna unguiculata subsp. sesquipedalis), and hyacinth bean (Lablab purpureus) are used in a similar way. Green beans are known by many common names, including French beans, string beans, snap beans, snaps, and the French name haricot vert. They are also known as Baguio beans in Philippine English, to distinguish them from yardlong beans.
They are distinguished from the many other varieties of beans in that green beans are harvested and consumed with their enclosing pods, before the bean seeds inside have fully matured. An analogous practice is the harvest and consumption of unripened pea pods, as is done with snow peas or sugar snap peas.
Source: Wikipedia