A removable extra storage space that you can carry everywhere and transfer via high speed cable through USB-C port.

Portable SSDs are three to six times faster at transferring files than portable hard drives or desktop external drives. They're also more secure and much more compact and durable, and they run cooler on less power.

Typically, external hard drives are more affordable and most importantly are available in larger capacities. However, on the other hand, SSD's are predominately more robust and smaller in size. This makes SSD's extremely portable and easy to use on the go.

If you are a photographer or videographer, a portable SSD drive is an invaluable tool and absolutely worth it. Fast portable SSD drives are extremely helpful when transferring large amounts of files for clients or personal use. They are more reliable than SD cards and a better option while on-the-go than a traditional platter-based external hard drive.

SSD and HDD are both important tools for photographers and videographers and should be used for different purposes. In an external SSD drive there are no moving parts—this makes an SSD drive faster and more reliable in the short term than an HDD. Also, a portable SSD drive is an excellent tool for transferring photo or video files while you are out on an assignment or on an adventure. An HDD drive, on the other hand, is a better archival file storage system because of its gigabytes-per-dollar ratio. Think of your SSD drive as the ideal choice for throwing in your camera bag before you leave the house for a shoot, while your HDD sits safely at home on your desk storing all the photos and videos that you’ve taken in the months and years before. 

Like all camera tech, you will notice that your SSD drive will get slower over time. SSD’s typically have a limited number of read/writes and will slow down as you put more files on them. This is why it’s great to use them as storage on-the-go, transfer those files to an archival drive, and then wipe them before your next job. Drives with larger capacities will take longer to slow down, which is one reason that a 1TB drive may be a better choice than a 256MB drive.

The answer is YES.
If you have a modern computer with high quality interface and as technology further progresses, you can expect the external SSDs to have very similar performance as the internals or even better in specific cases.

One obvious benefit is speed and reliability. Using non-volatile flash memory provides immediate access to files on the drive and there are no problems with impacts. With no moving parts, portable SSDs will take much more punishment at the bottom of your bag!

Adding a solid-state drive (SSD) is the single biggest hardware change you can make to speed up a laptop. It makes everything faster; booting up, shutting down and launching apps will all occur in the blink of any eye when compared to traditional hard drives.

There is not a distinction to the way both drives write/read data, but the main difference is in their connection to computer. The internal SSDs will connect via SATA or m.2, while the externals will connect through USB or eSATA.