Here is a paste from the Acronis site:
What is the difference between creating an image with Acronis True Image 2010 and using the embedded "Disk Clone" tool?
The "Backup" wizard of Acronis True Image 2010 creates an image file for backup and disaster recovery purposes, while the "Disk Clone" tool simply copies/moves the entire contents of one hard disk drive to another. Here's how both tools work and when you should use them.
When you create an image with Acronis True Image 2010, you get an exact copy of your hard disk, a disk partition or individual files or folders (you make this choice when you create the image archive). If you choose to back up a hard disk drive or a partition, then every portion of the hard disk that has data written to it (sectors) is saved into a compressed file — or multiple files if you prefer. You can save this image to any supported storage device and use it as a backup or for disaster recovery. (Note: if Acronis True Image cannot identify the file system, it creates a sector-by-sector image of the disk. This image is not compressed and the image file will be the same size as the disk being imaged.)
When you use the "Disk Clone" tool, you effectively copy/move all of the contents of one hard disk drive onto another hard disk drive. This function allows you to transfer all the information (including the operating system and installed programs) from a small hard disk drive to a large one without having to reinstall and reconfigure all of your software. The migration takes minutes, not hours, but it is not generally used as a backup strategy.