This page of the OER Commons Help Center categorizes these licenses "No Strings Attached," "Remix and Share," and "Share Only," going from the least restrictive to the most restrictive.

OER, the 5Rs, and Creative Commons: The Shortest Possible Introduction -- These slides give a step-by-step explanation of the licenses and the 5R's. It was created by David Wiley of Lumen Learning and is a CC BY license, meaning that you must attribute it to him and can use it any way you wish.

This graphic shows the six main licenses for OER, ranging from most to least free:

foter, CC BY-SA 3.0 <https://creativecommons.org/licenses/by-sa/3.0>, via Wikimedia Commons