HDD or hard disk drive refers to a spinning disk with magnetic traces. The traces are read or modified as the disk spins to read and write data.
SSD is or solid state drive refers to use of non moving circuits to store data.
- A spinning disk retards motion. as such, moving a laptop with HDD running puts a lot of strain on the HDD bearings, and platter (disk). Jostling about a laptop in use is a quick way to harddrive failure. SDD because there's no moving parts will not suffer as easily.
- HDD's have latency from a few areas. If you want to read a point in a file contained at a particular physical location on the disk, the read head has to move in to that location (seek time) and the disk has to rotate to that point (rotational delay). Again, since there's no moving parts, you can just read off the SSD, and the delay is circuit based. The result is dramatically improved IO.
- SSDs generally use less power. Generally
.http://www.tomshardware.com/reviews/ssd ... 269-7.html
HDD's generally cost a lot less to get the same space as an SDD. That said, I've found it worth it to rely on removable SD cards, USB keys and my home network to store loads of data. I use SSDs in my laptop for faster general use. Even my lowly eeepc901 is chugging along on an ssd.