While the underlying technology in all hard drives is essentially the same, it is the size of the different types of hard drives that sets them apart. Laptops are purchased primarily for their portability, but there is a growing attraction with laptops due to their esoteric value. A specific example of this would be the MacBook Air which sells itself as "Thin as always" and has a maximum thickness of just over ¾ of an inch. A typical hard drive used in a desktop computer system has an overall height of one inch.
The three most popular hard drives sizes, technically referred to as form factors, are the 3.5-inch drive, the 2.5-inch drive and the newest offering the 1.8-inch drive. At one time where was a 5.25-inch form factor offered but that size has been discontinued, as well as what was known as the 3.5-inch half height which was 60 percent taller than the current generation of 3.5-inch drives.
The most common drive interface for both laptop and desktop computers is what is known as IDE, which is the acronym for Integrated Drive Electronics. There is a distinct difference between the laptop and desktop IDE interface with the desktop IDE using a 40-pin data connector and an independent Molar connector for power. The 2.5-inch and the 1.8-inch form factor drives use a 44-pin connector and a 50-pin connector respectively with both employing an integrated power connector. The latest iteration, known as a ZIF socket, does not use pins instead opting for a thin receptacle that accepts a flexible sheet containing conductive traces to carry both the power and data. The ZIF interface is routinely found in iPods but is also finding its way into laptops and other devices that require storage.
The latest generation of hard drives are technically known as SATA. These drives, in both desktop and laptop environments, use an entirely different cable type. The advantage of a SATA drive over the legacy IDE drive types, also referred to as ATA and PATA, is the speed in which data can be transferred.
Solid State Disks
There is yet another technology working its way into the mainstream, the Solid State Drive, more commonly referred to as SSDs. Unlike their predecessors, SSDs are not a mechanical storage media but rather solid state, much like the flash or thumb drives that are quite common. These drives are small, fast, use very little power, and are considered to be quite rugged. At the same time, as with any new technology, it is yet to be seen how well these things will perform in the longer term.