According to David Wiley of Lumen Learning, open content refers to "any copyrightable work (traditionally excluding software, which is described by other times like "open source") that is licensed in a manner that provides users with free and perpetual permission to engage in the 5R activities:
1. Retain - the right to make, own, and control copies of the content (e.g., download, duplicate, store, and manage)
2. Reuse - the right to use the content in a wide range of ways (e.g., in a class, in a study group, on a website, in a video)
3. Revise - the right the adapt, adjust, modify, or alter the content itself (e.g., translate the content into another language)
4. Remix - the right to combine the original or revised content with other open content to create something new (e.g. incorporate the content into a mashup)
5. Redistribute - the right to share copies of the original content, your revisions, or your remixes with others (e.g. give a copy of the content to a friend)
A creative commons is a "some rights reserved" license that allows a copyright holder to grant permission to others to use the work while maintaining the rights to their work (so they still get credit for it). There are different levels of creative commons licenses, but in some cases, this allows a work to be changed and republished under the same license.
Imagine is a port of Creative Commons: Free Photos for Bloggers by foter.com Image is licensed CC-BY-SA