Here are two articles describing Environmental Graphic Design and Experiential Graphic Design. In 2014 SEGD changed the "E" from Environmental to Experiential. This was done to recognize the rapid expansion over the last decade of the scope of what this profession does. Experiential encompasses all of Environmental Graphic Design, but expands it to include digital technologies, content (such as video, images and stories) and most importantly the notion of interaction.
From an educators perspective the article Towards an Experiential Future by Justin Molloy provides a very good perspective of how the profession is evolving.
Finally here is a link to the SEGD presentation, What is Experiential Graphic Design which would for faculty and career counselors to show students interested in the field.