Two kinds of portable storage
Both external drives and flash drives plug into a computer and hold files you can carry around. They look like different tools once you use them, though. An external drive is a larger device, often the size of a deck of cards or a paperback, meant to hold a lot of data. A flash drive, also called a USB stick or thumb drive, is a small pocket-sized stick meant for moving a modest amount of data from place to place.
The right choice depends on how much you need to store, how long you need to keep it, and how roughly the device will be treated.
What is inside
External drives come in two main styles. Some contain a traditional hard disk with spinning platters. Others contain solid-state storage, which has no moving parts. The inside matters because it affects speed, noise, size and sturdiness. If the difference between the two technologies is new to you, our overview of solid-state drives explains the basics.
A flash drive uses flash memory chips with a small controller, all packed into a tiny case. There are no moving parts, which helps it survive a drop in a bag, but its small size makes it easy to lose and easy to damage at the connector.
Capacity
External drives typically offer far more room than flash sticks, and they are the usual choice for large collections of photos, video and general-purpose copies of your files. Flash drives are available in a range of sizes, but they are typically used for smaller jobs: a presentation, a few documents, an installer or a set of files to hand to someone.
Whatever the label says, the usable space will be a bit lower once formatted. The reasons are covered in our article on why drive capacity looks smaller than advertised, so a small gap is not a sign of a faulty drive.
Durability
Neither type is built to last forever, and neither is a safe place to keep the only copy of something important.
- Hard-disk external drives contain moving parts. They are generally more vulnerable to drops and knocks, especially while running. Handle them gently and set them on a stable surface.
- Solid-state external drives tolerate movement better, though they can still fail from other causes.
- Flash sticks survive many everyday bumps, but connectors can bend or break, and they are easy to run through the wash or leave in a pocket.
Heat, moisture and unsafe removal can also damage any portable device. Lifespans vary widely, so nobody can promise how long a particular device will last.
Best uses
Flash drive: Good for moving a few files between computers, carrying an installer, or sharing something with someone without internet access. Treat it as a courier, not a vault.
External drive: Good for extra storage, keeping a copy of your photos and documents, and holding larger files that do not fit comfortably on your computer. It is a common tool for the local side of backup basics, and a sensible companion to online services when comparing local and cloud backups.
An important caution is that a copy of your files on a single portable device is better than nothing, but it is still just one copy. If that device is lost, damaged or fails, the data goes with it. Testing that you can actually get files back is part of restoring backups, and it is worth doing occasionally.
Connecting them
Most portable storage connects over USB. The connector shape and the port’s capabilities vary, so a device may work but run more slowly on an older port. Our explanation of USB ports and cables covers the differences. If a larger drive does not get enough power from a port, using a different port or the cable that came with it may help. Avoid unpowered hubs for large drives when possible.
Compatibility is another factor. A drive is formatted with a file system, and not every computer reads every one. If a drive works on one machine but not another, that is usually the reason, and the details are in our article on file systems in plain language. Reformatting erases everything on the drive, so copy your files off first.
Safe habits
- Eject before unplugging. Use the operating system’s safe-removal option so that any pending writes finish. Pulling a drive out mid-write can corrupt files or even the whole file system.
- Keep it tidy. Label the device and keep a note of what is on it, so you do not have to plug in unknown sticks to find out.
- Be careful with unknown drives. A stick found or received from an unfamiliar source can carry malware. Do not plug it into a computer that holds important data.
- Replace aging devices. Errors, slowdowns, odd noises or files that will not open are reasons to copy everything off and retire the device. Our guide to the warning signs that a drive is failing goes through them.
- Wipe before passing it on. Deleting files is not the same as erasing them. Before selling or giving away a drive, read about wiping drives.
Which should you choose?
If you are carrying a few files for a short time, a flash stick is simple and convenient. If you want a roomy, reusable place to keep copies of your files at home, an external drive is usually the better fit. Many households have both and use them for different purposes.
Whichever you pick, buy from a reputable seller, be wary of devices priced far below normal, and follow the maker’s official instructions for setup and safe use.