Things to consider

SSDs (Solid State Drives) allow a computer to boot up in no time, and let you save and access files much faster than standard hard disk drives. SSDs have no moving parts, so they’re more durable and reliable, with better performance. And because nothing is moving inside the drive, SSDs are virtually silent.
In desktops, SSDs are normally used as secondary drives that can store the operating system, demanding software or your most commonly used programs. This really reduces load times - perfect for high-performance PCs or gaming setups.

When you’re deciding on which capacity hard drive to go for, it’s important to think about how much you’ll be wanting to store on it.
500GB is enough for backing up a single user's important documents, while a whole family looking to store films, music and photos will need at least 1TB. If you're looking for a storage device to back up project files from creative software, anything over 1TB is recommended, as these types of files can be huge.
The main benefit of a portable drive is that you can plug it into different computers and work on the same stuff in different locations. This portability and flexibility is great for students who want to continue their studies in the evening, or for anyone that needs to take work home from the office.
If you need to back up quickly on the go, an external SSD is small enough to fit into any bag or case without worry. You can’t do this as easily with a large external desktop hard drives – these are best left connected to a desktop PC when you’re backing up files and folders.

External hard drives are usually simple to get up and running, and you can easily unplug them for use on a different computer. So, if you want to share files between different computers (taking work home with you, for example), go for an external hard drive.
If you’re not too fussed about portability, internal drives come with a variety of benefits that include speed, price, and protection inside your computer. If your machine allows for a second internal drive to be installed, and you’re happy to take that task on, an internal drive could be right for you.