Use Setup Assistant or Migration Assistant to move data from an older Mac to a new Mac
Another scenario in which it would be desirable to do a full-volume clone is when you have purchased a new Mac and you would like to move everything from your old Mac to your new Mac. When you get a new computer from Apple, though, it has a specific version of OS X installed on it, and further, a hardware-specific "build". Your new Macintosh cannot boot from the older version and build of OS X that is installed on your older Mac, so simply cloning your old Mac onto your new Mac won't work. Due to this limitation, we recommend that you use the Setup Assistant application (runs on your Mac's very first boot) or the Migration Assistant application to migrate content from your old Mac to a new Macintosh. You can migrate either directly from the hard drive installed in your old Mac or from a backup of your old Mac (e.g. if your old Mac's hard drive had died). Once you have migrated your user accounts and applications using Setup Assistant or Migration Assistant, you can continue to use Carbon Copy Cloner to back up your Mac to the same backup volume that you were using for the old Mac.
Apple Kbase #HT2186: Don't install older versions of Mac OS than what comes with your computer
Apple Kbase #HT2681: What's a "computer-specific OS X release"?
Apple Kbase #HT3322: Mac OS X 10.6: How to use Migration Assistant to transfer files from another Mac
Apple Kbase #HT1159: OS X versions (builds) included with Intel-based Macs