When referencing a computer case design, an external drive bay is one that is accessible from outside the computer, such as a drive bay that houses an optical drive (CD or DVD). An internal drive bay is not accessible from outside the computer, such as a bay that houses a hard drive. There is no need to have physical access to the hard drive so it does not need a "door to the outside" like a CD or DVD drive.
The slot on the front of a PC where an optical disk drive, floppy disk drive, and other accessories can be insterted
Drive bays are the places where storage devices are stored, such as the hard drive.
then we connect it with external usb device
Of course it would. If you are copying your C Drive onto an external drive, then are copying it to an external drive, aren't you?
As long as you have an open bay of the right size, just the hard drive is all you should need, maybe two screws. If you don't have an open bay, you can use an external hard drive that just plugs into a USB port.
You can purchase form factors (minus power-supply) for as low as $32.00 US
The volume label of an external hard drive refers to the string, which shows before the drive letter if you were to look at the drive using My Computer. For instance, if it is written External Drive:E, then the label is External Drive.
The fastest type of external hard drive would be a external 3.0 USB hard drive.
A USB flash drive is a type of external drive. If you meant external drive as an external hard drive, then no, there won't be any difference in the pictures. However, if you're archiving, I'd suggest an external hard drive, because they work best for archiving.
external bay
You can completely clear your external hard drive by formatting it.
You can certainly move Windows to an external hard drive but Windows will not boot directly from an external drive. If you are running Windows in Parallels (See links below) you can have Parallels installed on the Mac's drive and then have your Windows virtual machine on the external drive.
You can use the universal kit to sexly fit the hard drive into the drive bay.
The external hard drive is a great way of backing up your data.