Spanish into English and English into Spanish
It is conveying a message verbally from one language into another in real time. Traditionally, two interpreters work in a soundproof booth, each taking a turn every 20-30 minutes. This is due to the extreme speed and intense pressure of simultaneous interpretation involving an average of 150 words per minute. Every participant in the audience has an individual receiver with earphones. A great example of this type of meeting is what we see at the United Nations.
It is conveying a message verbally from one language into another but there is a pause before the interpreter speaks to the audience. The interpreter generally works next to or near the speaker in the same room. An example is what is done in beauty contests like the Miss Universe Pageant.
It is conveying a message from one language into another in written form. The translator works from home or an office and receives and sends documents electronically. A translator can normally translate between 2000-3000 words a day.
Tip: To help you understand the difference between an interpreter and a translator, think of an interpreter as someone who speaks and a translator as someone who writes. Easy!