Interpreting vs. Translating
Broadly speaking, interpreting means that the interpreter listens to the spoken word and renders the text into another language by speaking. Translating, on the other hand, always means that a written text is read and set down in writing in the target language.
Incidentally, neither the interpreter's nor the translator's job titles are protected. This means that theoretically, anyone might call themselves "interpreter" or "translator" even without having undergone the respective training if they consider themselves competent. This is the reason why professional interpreters and translators set great store on pointing out that they have earned their qualification in a corresponding university course taking several years.
Entrusting a conference or a translation job to qualified interpreters or translators means that the client can be sure that professional results will be delivered.