One difference between translation and interpreting is the durable nature of translation, compared to the ephemeral nature of interpreting.
Verba volant, scripta manent.
Admittedly, nowadays up-to-date technology allows for interpretations to be recorded – thus increasing access to them – but the nature of the interpreted content in question informs the way in which such recordings are used: the interpreted version of a speech can be used for many different purposes, but the interpreted version of an informal conversation would be less useful. Just as we only tend to write down what is important, only the most significant communicative or expressive acts will be recorded. In this way, recordings and sound reproduction imitate writing. However, for now we will only focus on written content: translation.