User Level: 

View Modes are used to configure the layout of content as the audience sees it.

These configurations are defined within the View Modes section of a Drupal site and they are applied within the Manage Display and Manage Form Display  configuration tabs of the different entities within a site.

View Modes are used in many different Drupal 8 components including field layout for all Node, Media, User, and Taxonomy entities, Views, and for embedding content objects via the Entity Browser.