Is "flash storage" the same "SSD"?

I'm looking to see if the two are interchangeable and if not what the differences are.

If the two in fact have a difference, perhaps adding devices or cases where each are normally used over the other.

Yes and no.

Flash storage is storage that uses electronically programmable and erasable memory modules with no moving parts. It refers to a very specific implementation of data storage. It can come in different packages though: wrapped in a hard, plastic envelope you slide in to your camera; mounted to a PCB stick with exposed connectors and docked inside your MacPro; or mounted inside a drive enclosure that's slid in to an existing drive bay.

SSD, or Solid State Drive, refers to an enclosed storage device that's meant to act as a disk for a computer, but is lean on details about what's inside the enclosure and being used to store the data.

Technically, "solid state" just refers to "electronics with no moving parts". So a "solid state drive" that used ferromagnetic fluids to store data is still an SSD.

And indeed, SSDs have been around for a long time with a variety of different solid state storage mediums inside of them to keep those 1's and 0's persistent. However, in this day and age, at the time I'm writing this, SSDs are generally filled with (you guessed it): flash-type memory modules. Though flash-based SSDs generally carry the property that their enclosure is built to mirror that of a typical 2.5" spinning drive disk enclosure with an SATA interface so that it can act as a drop-in replacement for a mechanical disk.

Credit for this answer goes to https://danielmiessler.com

Short Answer

Let's clear up the definitions:

Solid State Drive = a hard drive that has no moving parts

Flash memory = a method of permanently storing information without constant power being applied

Therefore, the answer to your question is No; Flash Memory is not the same thing as a Solid State Drive.

Flash memory is one implementation of an SSD. You can also create an SSD out of RAM; if you implement an SSD using RAM, you'll lose data when you turn off the power to the SSD.

Long Answer

SDD (Spinning Disc Drive) - a.k.a HDD (Hard Disc Drive)

• It is important to know the difference between a Spinning Disc Drive (SDD) and a Solid State Drive (SSD) to answer this question
• What is a Spinning Disc Drive?
• Spinning Disc Drives have moving parts
• Spinning Disc Drives are being phased out in favor of Solid State Drives (at least in consumer applications)

SSD (Solid State Drive)

• SSD simply means "a hard drive without moving parts"
• The Solid State Drive was developed to improve upon Spinning Disc Drives (moving parts are not that reliable and slow to read from memory)
• The SSD has been around for decades (contrary to popular belief)
• Recently, the technology has gotten better, so you see them in all newer comptuers

RAM (Random Access Memory)

• SSD's were originally achieved by using RAM as the method to store data
• RAM requires continuous power to be applied to retain data
• By using RAM, the hard drive no longer had moving parts
• The major downside of using RAM: you can never turn your hard drive off or else you lose all your data.
• Historically, RAM was/is used in conjunction with a Spinning Disc Drive or a Solid State Drive (since RAM cannot retain data once powered off)
• The upside of using RAM: RAM is super fast - faster than SSD's and flash memory

Flash Storage

• Flash storage is also relatively old technology, but started as a way to permanently store information without power being continuously applied (in contrast to RAM)
• Flash storage has traditionally had significant aging issues
• Basically you could only write to the memory a certain number of times before you would lose that section of the drive, and performance would generally get worse over time as well.
• As Flash storage improved (in the late 2000’s), manufacturers started making SSDs out of Flash memory instead of out of RAM.
• Modern SSD hard drives are Flash-based, so today, there’s not really a difference between SSD's and Flash memory.
• As stated above, SSD's are simply disks that have no moving parts, and Flash is the implementation that allows that to happen
• USB thumb drives have used Flash storage for a long time as well, but the quality of the Flash storage in USB's is typically much lower than the Flash memory used in SSD's. This means much worse performance for USB's than SSD's (but I believe current USB technology is improving to close the gap)

SUMMARY

• SSD just means a hard disk that doesn’t have moving parts; Flash is a type of memory that is very fast and doesn’t require continuous power (non-volatile)
• SSDs used to use RAM, but now use Flash instead. In short, you shouldn’t compare Flash to SSD just as you shouldn’t compare batteries to lithium-ion. In both cases the latter is a type of the former.

An SSD has flash storage inside but SSD is a special form factor, in most cases meaning that it is designed to fit in places that a normal 2.5" HDD would be installed. Flash comes in a huge range of formats from tiny cards for phones and cameras and in Macs it can be an SSD, mSATA, and PCIe form factors.

So if you have a flash device in the shape of a 2.5" drive it is an SSD. MacBook Airs, Retinas, new iMacs, and the new Mac Pro all use PCIe form factors giving even better performance.