So way back, when AutoCAD for Mac was first introduced, the product keys for the mac were different from Windows version of AutoCAD.
The great news is that starting in 2014, they are all the same!
AutoCAD for Mac 2011: 777C1
AutoCAD for Mac 2012: 777D1
AutoCAD for Mac 2013: 777E1
AutoCAD for Mac 2014: 001F1 or 777F1 *depends on what you have purchased!
AutoCAD 2011 [Windows]: 001C1
AutoCAD 2012 [Windows]: 001D1
AutoCAD 2013 [Windows]: 001E1
AutoCAD 2014 [Windows]: 001F1
AutoCAD 2013 LT for Mac: 827E1
AutoCAD 2014 LT for Mac: 057F1 or 827F1 *depends on what you have purchased!
AutoCAD 2013 LT [Windows]: 057E1
AutoCAD 2014 LT [Windows]: 057F1
This is now a bit aligned with all the Mac Compatible Products regardless of the operating system that it is installed on.
Thanks to Avto Chachava for sharing this tip with the community.
Epilogue [VERY IMPORTANT!]
If you have purchased AutoCAD 2014 on Windows, you can use the same product key for installing on Windows and Mac versions of the product. [Product Key: 001F1]
If you have purchased AutoCAD 2014 on Mac, you must use the product key for the mac version only [Product Key 777E1].
The backend database will be checking the version that you have bought and they must sync before an activation will take place.