Creative Commons licenses have different terms that can be mixed and matched to create six different license combinations. They also come in three kinds of code: Human readable, lawyer readable, and machine readable. 

The following video from CC New Zealand is a great five minute introduction to all the parts of a CC license. 

CC Kiwi video

After watching the video, if you still want more detail about how the licenses work and what the spectrum of licenses looks like, CC has a nice concise page that explains it all in text. 

http://creativecommons.org/licenses/

Here is a quick exercise to test your understanding of CC licenses. 

Other concerns: Jurisdictions, license compatibility