HDDs were first introduced by IBM in 1956 – yes folks this is nearly 60-year old technology. Uses magnetism to store data on a rotating platter. The speed at which the platters spin helps determine the read/write times. Major advantage of an HDD is that it is capable of storing lots of data cheaply. (TB of data)

SSD (solid state drives) uses what is called NAND-based flash memory. This is a non-volatile type of memory. It Does not have a mechanical arm to read and write data. it instead relies on an embedded processor called a controller to perform a bunch of operations related to reading and writing data. The controller is a very important factor in determining the speed of the SSD.  Good controller technology is often what separates an excellent SSD from a  ~good one.

~7mins start @ 3.15min.

IDE = Old
SATA (Serial ATA) = New
Types of sata:
SATA 3Gb/s (also marketed as SATA 2 or SATA II),
or the newer and faster SATA 6Gb/s (aka SATA 3 or SATA III).

Common form factors (smaller ones are for laptops):
– SSD: 1.8”, 2.5”, or 3.5”  (inch)
– HDD: 2.5”, or 3.5”

Notes:
1.  SSDs are more expensive than hard drives in terms of dollar per gigabyte.
From 5 cents per GB for HDD to  and 23 cents per GB for  SSDs.
2.  SSD units top out at 4TB or 6TB (6000GB) but they are rare and very expensive.
3. Fragmentation: Because of their rotary recording surfaces, HDDs work best with larger files that are laid down in contiguous blocks. When the computer writes data to drive, it does so in „blocks” that are ordered sequentially from one side of the drive’s platter to the other. Fragmentation happens when those files get split between blocks that are far away from each other. The hard drive then takes longer to read that file because the read head has to „visit” multiple spots on the platter
4. SSD can be 4 times faster then HDDs in Read / Write operations.

Video- Types