Tangerine: A generic name given to numerous small orange citrus fruits, more commonly known as mandarins. Satsumas are simply a different variety and clementines are a hybrid between the tangerine and the sweet orange.
Orange: The fruit of a tree of the genus citrus .It is usually round, and consists of pulpy carpels, commonly ten in number, enclosed in a leathery rind, which is easily separable, and is reddish yellow when ripe. There are numerous varieties of oranges; as, the bitter orange, which is supposed to be the original stock; the navel orange, which has the rudiment of a second orange embedded in the top of the fruit; the blood orange, with a reddish juice; and the horned orange, in which the carpels are partly separated..