The term SSD drive is an acronym for Solid State Drive, these drives store data even when powered off. They consist of a special memory with no moving parts. The SSD hard drives replace older platter-style mechanical hard drives. They are much faster, and most modern computers use them. As they have become the new standard for storage, prices have also dropped considerably over time.
The 2.5” SSD is larger in size than M.2 drives. It is used in either a computer that is not M.2 compatible or for extra storage when M.2 slots are filled. These drives can also easily be used as external drives. These drives are much larger than M.2 drives. Sometimes when using these drives, especially in older computers a special mounting kit must be used. These kits are relatively inexpensive and take a little more time and effort to install. The 2.5” SATA SSD is fast compared to old-fashioned mechanical hard drives. These are the least expensive of the three options discussed.
The next option is the M.2 SSD, which can be used in computers that have an empty space in the M.2 port they use. They are much smaller than 2.5” drives, however, unlike them, they require more accessories to be used as external drives. These drives have the same speed as 2.5” drives and are normally more expensive.
The M.2 NVMe SSD is used with a specialized port that takes advantage of its features. Note in some cases this slot is backward compatible (able to be used by older versions of hardware), with the M.2 SSD. These slots are often available in most currently manufactured computers. These are the most expensive type of drive; however, they are also much faster than the other two versions.