What is the difference between Permissions and Licensing on the site?
Permissions dictate what other Aviary users can do with your file on Aviary (from a technical perspective). You can turn on and off access to certain aspects of your file using your permission settings. Licensing dictates what people on Aviary can do with the flattened version of your file off of Aviary. This is not technically enforced and instead relies on people adhering to the licensing terms set in the Creative Commons license you pick.
