Let’s start with an analogy.
You are giving a presentation to a group of people in a meeting room. You have a PowerPoint presentation on the screen.
During the course of that presentation, part of the time you will be facing your audience, looking them in the eye, and talking directly to them.
At other points, you will turn your back on the audience and speak to a slide on the screen. You might be pointing to some figures, a chart, or some bullet points.