Interpretation and translation are two closely related linguistic profession. Yet they are rarely performed by the same people. The difference in skills, training, aptitude and even language knowledge are so substantial that few people can do both successfully on a professional level.
On the surface, the difference between these two professions is the medium: the interpreter translates orally, while a translator interprets written text. Both presuppose a certain love of language and deep knowledge of more than one language.
Most people think they are the same, but only the professional that worked for both can really tell the experience.
The key skills of the translator are the ability to understand the source language and the culture of the country where the text originated, then using a good library of dictionaries and reference materials, to render that material clearly and accurately into the target language. In other words, while linguistic and cultural skills are still critical, the most important mark of a good translator is the ability to write well in the target language.
Even bilingual individuals can rarely express themselves in a given subject equally well in both languages, and many excellent translators are not fully bilingual, to begin with. Knowing this limitation, a good translator will only translate documents into translator’s native language. This is why we only translate into our native language, in addition to our subject matter expertise.
An interpreter, on the other hand, must be able to translate in both directions on the spot, without using dictionaries or other supplemental reference materials. Interpreters must have extraordinary listening abilities, especially for simultaneous interpreting. Simultaneous interpreters need to process and memorize the words that the source-language speaker is saying now, while simultaneously outputting in the target language the translation of words the speaker said 5-10 seconds ago. Interpreters must also have excellent public speaking skills and the intellectual capacity to instantly transform idioms, colloquialisms, and other culturally-specific references into analogous statements the target audience will understand.