Ausgabe = when the text (foreword etc.), images, formatting, or something else has changed Auflage = books are printed in batches; when one batch is sold out, the next batch is printed. These batches are numbered, and this is the Auflage. So the 1. Auflage and 2. Auflage are identical, but the 2. Auflage is printed later. The 2. Ausgabe contains changes compared to the 1. Ausgabe.