Featured images are pre-formatted into some of our content types and templates such as news posts and departments. Oftentimes the feature post is highlighted in the header of content and previewed as a thumbnail on another page or list.
The add media option provides the admin with more flexibility to post media throughout their content. Simply put your cursor where you want the media to inserted and select add media to start the process.
Media input with the “Add Media” method will not show up in teasers lists, however. To have an image display in the teaser view and to take more direct control over the appearance of a post, simply check the “Hide Featured Image” checkbox on the edit page after selecting a featured image.