There are basically two different types of hard drives on the market. One is a spindle hard drive and the others is an SSD or solid state drive. The spindle drive has been around for a long time. These drives are found in 2.5 inch and 3.5 inch drives. 3.5 inch drives usually need auxiliary power. 2.5 inch drives usually run on bus power(gets power though data connection). These drives are electro-mechanical data storage devices. The platters rotate between 5400-7900 rpm and a magnetic arm moves across the platter to read and write data. The read/write speeds of these drives are around 115-250 MB per second. An downfall of a spindle drive is that the read/write speeds are slow and they can easily break because they have moving parts. The pros are they hold large amounts of data and are the most cost effective.
The 2.5 inch drive is usually a portable drive that runs at 5400 rpm on bus power. They are most common in laptops, but most new computers use solid state drives and portable external hard drives. It is one of the more common drives found in box stores and it is most likely a consumer drive. The 3.5 inch drives runs at 5900-7900 rpm. Usually, the faster the rotation the faster the read/write speeds. They offer the most bang for the buck but usually require separate power. These drives can be found as a desktop internal drives(mostly replaced by SSD’S), NAS drives or external non-portable drives. Spindle drives come in consumer and enterprise variants.
Enterprise drives are usually made for NAS(network attached storage) or servers and are much more reliable, rated for around 1 million hours and have better warranties. The main spindle drive brands are Western Digital and Seagate. Toshiba is also in the market. Hitachi or HGST used to make spindle drives but Western Digital bought the company. Examples of Enterprise drives are Western Digital Red Pro and Seagate IronWolf Pro. You can get enterprise hard drives in external drives. I use one by Glyph, Glyph does not make drives. Most likely it uses Western Digital or Seagate. I usually just call the manufacture and they will tell you the exact specifications.
If you are ever wondering which drives are the best, a company called Backblaze publishes the failure rates of the drives they use. Backblaze is a personal and business backup service. I use and love this company. They backup your computer and all hard drives for $6 a month but you can get a discount if you pay for the year. This is not an offsite cloud like google drive but a backup solution. The process is automated in works in the background.
SSD or Solid State Drive
The SSD is a flash memory drive that has no moving parts and work with semiconductors and NAND style chips. They are lighter and more portable, require less power and crazy fast. SSD’s are found as internal hard drives as well as external drives. SSD’s two most common form factors are 2.5 inch and M.2. Most 2.5″ SSD’s run an SATA which was developed around 2000. M.2 drives run on both SATA and PCI Express. Some M.2 drives running PCI Express also support NVMe. Most computers these days are using SSD’s are the main hard drive. The speed of the drives lets you computer boot up and work at much faster speeds. The down side is they are more expensive(but prices are dropping) and they don’t hold as much data. It is typical these days to see smaller SSD’s in a laptop to run your OS and all other data saved on external drives instead of the internal SSD. This is the way I have been working the last 6 or 7 years. I actually made on old 2010 MacBook Pro useable by replacing the spindle drive with an SSD. SSD speeds vary on a variety of factors but read/write speeds are around 450-3000 MB per second. Just like any drive they do have a limited life and will slow down when the reach the number of times they can read/write data.
I presently use an internal SSD in my laptop, an external SSD as my working drive, two external spindle drives one enterprise and one consumer, and four Western Digital NAS Red drives in a Qnap Network Attached Storage running Raid 5. I would suggest that anyone buying a new computer of any kind do not buy one with a spindle drive.
If you would like to learn about the differences in SD cards check out this blog I wrote https://www.jcwphoto.com/sd-cards-are-not-created-equal/