I'm confused and don't know which one to download:
"Todo Backup" copies all the files in a partition to a disc image. The size of the image will be the total size of all the files on the partition.
"Disk Copy" does an exact sector-by-sector clone of the hard-drive. The size of the clone will be exactly the same as the total size of the hard-drive. The image may contain multiple partitions, and also files that were previously marked as deleted but physically still exist on the drive (i.e., files that were not securely erased).