What are Drupal Apps? I've been seeing the use of Apps. What are drupal apps? 

Are they just glorified Features with a backend UI? What are the differences between the two on a lower level? The apps project page only gives a pretty high level understanding.
Have you read the Open App Standard http://groups.drupal.org/open-app-standard/oas ? Here's an excerpt that might help:


  What is an app? Before we say what an App is it’s helpful to know who
  it’s for: An App is for the end user, typically a non-technical user
  of a Drupal site such as the site administrator....
  
  ...Technically, an App is a collection of new or existing Drupal
  functionality, including Modules, Features, and Themes along with some
  simple additional code that publishes the existence of the App to the
  rest of the App infrastructure.
  
  What distinguishes an App from a Module or Feature is that the App
  includes all of the additional polish, end-user UI, configuration UI,
  sample content, and documentation that are needed to fully meet a
  specific need. Whereas Modules and Features are more developer-centric
  and provide building blocks for larger functionality, Apps are larger
  blocks of completed functionality.