A:
Yes of course it is possible to back up any drive onto any drive. But you have to pay attention to the size of the data that you wish to backup and the size of the drive you are placing your data onto.
All you have to do is go to My PC and figure out which hard drive letter belongs to the drives that you are dealing with.
By default your pc's drive is usually the C: drive. And if you are using a namebrand pc then there may be a D: partition on your main drive. This in basic terms means that you have one hard drive inside your pc that has been partitioned (split) into two different drive letters, which are C: and D: drives.
Now it sounds like you are dealing with external drives or other internal drives. It doesn't really matter. What matters is that you know exactly what data you want to back up or copy and paste.
Lets say I have a laptop with one internal drive that is partitioned into two drives, C: and D:. Plus I have a DVD Drive which has drive letter E: assigned to it.
So I connect two usb external drives to the pc, windows detects the drives and automatically assigns a drive letter to them both. It assigns F: and G: to the two new external drives.
Now I want to EXPLORE both drives and make sure I know which data I want to copy and paste into the other drive. You may or may not know this but copy and paste is not just for text on a web page. You can highlight files in a folder and copy them and move them from one folder and past them into another folder. Same thing with files and folders on different drives. Select them (highlight them) right click and choose copy, then open (explore) the destination drive which you want to back up the files onto and right click and choose paste. Then every file you selected and copied from the original drive will then be copied to the destination drive.