Radio theater is a general term that refers to any form of dramatic presentation on the radio. This could include radio series, readings, adaptations of plays, novellas, etc.
The Original-Hörspiel falls under this general classification but is clearly distinguished for the following reason: the Original-Hörspiel is the original work of an author, written specifically for radio, and is a singular, complete work of art. Thus, while all Hörspiele are radio theater, not all works of radio theater are Original-Hörspiele.
The word hörspiel, as noted by the Austrian author Ernst Jandl, is a double imperative: Hör (listen) + Spiel (play), while the word original signifies the original creation.
