It’s been awhile since Drupal 8 has released. With all the new architecture and eye-catching new technologies, Drupal 8 has a new architecture in place for content and configurations.
In Drupal 7, entity concept was reduced lately and was very limited. Later on, entity API module extended the concept but it had very limited coverage. In Drupal 8, entity API has been extended to a feature complete, object-oriented based solution which offers high flexibility site building/development.