There is a huge difference:
- With
dd
(any any other method to write to the drive with lots of data until it is full) you are overwriting old data with new data. Compare it to getting a pencil written notebook and filling all the pages with new text. - With the 'secure erase yourself' command used by DBAN (or other tools, such as via hdparm) you tell the drive to fully erase itself. You do not generate data and send it to the drive. The drive itself does all the work.