Why are there two default image options in an image field When you create a field of type image in Drupal 7, there are two default image fields. 

One is in settings and the other is in field settings. There is a message with each of those two settings, but I still don't understand how they are different. In each case, they upload to the sites/default/files/default_images folder. 

What is the difference between the two settings fields?
One is the default image information for that field as a global entity, while the other is specific to that instance of the field. Fields can be re-used across different content types, so the global default would apply to every content type that used that field, unless those content types override that behaviour with their own specific default.