Q. What are the advantages of disk image backup over traditional file backup?
A. Traditional file backup is so-called because it literally copies each individual file on a computer to a backup destination. In its most basic form, this can involve a user selecting a folder such as 'My Documents' and writing it to a CD or external hard disk drive. A disk image backup works at a level 'below' individual files - it copies the actual content of the hard disk drive, which of course includes all the files on it.
Since all data on a hard disk drive is captured with the disk image approach, restoration of the entire system to a 'bare metal' (i.e. no operating system installed, etc. - the computer is completely blank) system is much faster. This is because everything, including the operating system, all files (even 'open' files that were in use when the backup was taken) and configuration is restored in one pass with no need for any manual effort on the user's part.
The Acronis True Image Echo family does also include file backup functionality, so that a subset of files can be backed up should the need arise. Impressively, Acronis True Image also boasts the ability to restore individual files from the disk image backup rather than restore the entire system.
With Acronis, users truly have the best of both worlds here.