Display Modes can be a little bit confusing when you first start out.
The two different types of Display Modes that can be configured are Form Modes and View Modes.
Form Modes are used to configure the layout of the forms that your content providers use to create content.
View Modes are used to configure the layout of content as the audience sees it. This can take on many different forms such as list of available embeddable media options in the Media Browser to being displayed as Rendered Content in a view.
While it's a little bit confusing when you're first starting out, these different display modes are actually very helpful. These display configurations provide us the ability to create multiple displays of an object, which we can then use in different ways.
Let's take a look at an Image media type that you might want to display: