Disk Utility vs Carbon Copy Cloner - How to clone your drive with Apple's built-in app
DiskUtility is pretty bare-bones when it comes to duplication. You can use it to create a clone, but you have to kick it off manually, and that's about the limit of its features.

Both CCC and SuperDuper have a pretty similar feature set, which includes a lot of features required for convenient backups, like:


Scheduling
Filtering files
Support for bootable volumes
Scripting before and after the run (do something more custom)
Mount/unmount the drives so they don't normally appear on your desktop
Smart copying - only copies changes, not the whole drive. This makes it much quicker.
Block-copy of the drive - available in certain cases. Identical copy, not file based.


Under the covers both are very much like (or perhaps implement) rsync. This is a free command-line tool included with OS X which you can use to duplicate drives. But, requires you to use the command line and learn the options. Not all that obvious or intuitive, but works very well.

Anyway, to answer the question:

Be aware - this will wipe the target drive


Find the target drive you want in Disk Utility
Click onto the Restore tab
Drag the source drive over to where it says Source (drive you're backing up)
Drag the Target drive to Destination (drive you're writing the backup TO).


THIS DRIVE GETS WIPED

Click Restore


As you can see, for each back-up, you have to do it all manually. With CCC, and other tools, you can schedule it to happen when you're away, as often as you want. eg. every night at 2am. You can also have multiple backups of different data to different place. eg. Whole drive weekly, and your important docs nightly.