There's no difference other than what's on them.
Soft data is stored on a data disk or hard drive. Where as hard data is printed.
They store digital information in a relativly permenent form. Some hard drives called 'Hard Disc Drives' store data magnetically on a metal disc. Newer hard drives called 'Solid State Drives' store data electronically on flash memory.
If you mean between hard drives and ssd's (solid state drives), then you need to read the wikipedia page on Solid State Drives, it has a comparison of the two technologies.
external hard drives
There are many places on the high street to buy hard drives for data storage like PC World. You can also find hard drives for sale on both Amazon and eBay.
Removable media, such as USB drives or external hard drives, can be easily detached from a device, allowing for portability and data sharing. Non-removable media, like internal hard drives or solid-state drives, are fixed within a device and cannot be disconnected without opening the device.
japseye water
method of storing data on two or more hard drives that work together?
Traditional magnetic hard drives use platters that spin and a magnetic head that applies negative and positive charges to the platters to record data in 1s and 0s. SSD drives are essentially flash drives similar to what is used in iPods. "Switches" in each memory "bank" are turned on and off with an electrical signal to record the data in 1s and 0s. SSD is faster because it does not have to "seek" for the location of the data on the hard drive.
bitlocker
You can perform a data recovery operation on your hard drives using free software such as Recuva. You can download Recuva for free from the Piriform website.
Without more information, there is not enough to conclude that there even is a difference.