How they store data
A hard disk stores data magnetically on spinning platters read by moving heads. An SSD stores data in flash memory chips managed by a controller that constantly moves data around.
Deleted files: a key difference
On a hard disk, deleted files often remain until overwritten. On an SSD, the TRIM command tells the drive to erase deleted blocks, often within minutes. This is why deleted-file recovery from SSDs is frequently not possible.
Failures
Hard disks often fail mechanically, with warning signs like clicking. SSDs tend to fail suddenly, through controller or firmware problems. Both can often be recovered with the right methods, but approaches are completely different.
What this means for you
Back up both types regularly. If an SSD loses data, shut the computer down immediately. If a hard disk makes noise, switch it off. In both cases, contact us for a diagnosis.
Important: Switch the drive off if it makes unusual sounds. Stop using the drive immediately.