The two terms are similar to each other. They both can be used to describe the logic and reasoning behind something, but there are differences. Logos goes into description about what it is trying to describe, while echos is more like using a metaphor and can possibly visually describe something. Since echos is a term that can be used visually, it is a term that is easy to apply in the media. Echos can be seen as something that is in some ways, an improved way of using logos in terms of logic and reasoning in the media.
Some things work better for the media than others. Logic and reasoning is something that is important for anything, the media is no exception. Having the right way to present that logic and reasoning is equally important. In terms of logic and reasoning, echos is a proper term to use in the media.
