1. Resources
 
  - Normal resource loading,
    environ.find_resource(resource_name, object)

    * Locale
    * Images
    * Glade files
    * Documentation

  - Directories
    To be able to extend.

  Can a directory be a normal resource (dict) or a special list/constant?

2. Library
   
   A resource container

3. Application
   
   Like a library in most senses, but has some additional features
   
   - Launcher script and main script
   - Translation

4. Uninstalled vs Installed
  
  - Installed structure, defined in setup.py
  
  - Uninstalled structure, defined in __init__.py for library
    and in launcher script or main.py for applications.