SSD hard drive, USB flash drive, whats the difference?

They are basically the same exact thing arent they?

Ghot said:

They are both... solid state. Made up of IC chips rather than spinning platters.

SSDs are generally installed inside a computer. USB sticks are used externally, as are External SSDs.
Windows doesn't like being installed on and run from, a USB stick.

What's the difference between flash and SSD storage? | PC Gamer

Even if the USB and SSD were identicle?

Ghot said:

I'm not sure what you mean by identical. Are you talking about same "size".
Same manufacturer?

There are three things here.
Three devices and the way they (connect) and [what they're used for]

USB flash drive (USB) ....[storing/moving backups or data]
External SSD... (USB or eSata) ....[storing/moving backups or data]
Internal SSD... (SATA or M.2) ....[operating systems, or data/backups storage]

Yes, what if they were 100% identicle, would Windows still want to operate from inside the computer?

Installing Windows to external media is something I just happen to have been experimenting with rather extensively about a week ago. But before I address that, just a little bit more about the difference between a flash drive, external SSD, and internal SSD.

There are some fairly speedy flash drives out there these days, but in general terms they are not going to be as fast as an SSD. But even more importantly, there is a world of difference in the controller that manages an SSD vs a flash drive. Flash drives don't have nearly the intelligence of an SSD built into their controllers. As an example, an SSD supports TRIM which is a critical element in maintaining performance on an SSD.

As for internal vs external SSDs, they are basically the same thing with the exception of the interface (either SATA or NVMe for an internal, USB for an external). You can expect better performance for an internal SSD, at least for the SSDs of an NVMe type.

Okay, back to installation of Windows: For a standard installation of Windows, this would need to be performed on an internal drive. However, it is possible to install windows to an external SSD or even a flash drive if you really wanted to do so. The installation method would be a bit different in that you would install Windows to a VHDX file (a virtual disk file) on the external media.

Note that Microsoft had a great solution for installing to external media such as flash drives called "Windows to Go" but that has now been removed from Windows. It did require special, certified flash drives that would present themselves to the system as a hard disk rather than removable media. These specialized flash drives also had a much higher endurance rating than your standard flash drives. That, by the way, is another difference between flash drives and SSDs - SSDs have a lot greater endurance than flash drives, in large part due to the maintenance tasks performed by their controllers.

Also, be aware that running Windows from a flash drive will yield abysmal performance, even on fairly fast flash drives, and simply intolerable on slower flash drives.

If running a copy of Windows on an external drive turns out to be something you absolutely want to play with, I can provide some instructions, just be aware that it would take me a while to write this up.

Try3 said:

This interesting thread raises an additional question in my mind.
Why do we never refer to trim for flash drives but only for SSDs?

Denis

Because flash drives don't support TRIM. Their controllers don't have the smarts to handle that.

EDIT: This is one of the main reasons that I am transitioning away from flash drives altogether. I'm accumulating NVMe drives which I swap in and out of external enclosures. They are wicked fast and relativly cheap now. A 500 GB NVMe can be purchased here in the US for under $40.