Arch Linux
to my knowledge, No version of Linux refers to drives via drive letters; usually it's something like /dev/sda or /dev/usb1 and so forth.
I installed Arch to a VM here but was unable to get a desktop environment installed (something wrong with my repository setup, so pacman couldn't update or install anything).
I tried a few things in the terminal but to no avail; I was able to "see" the USB drive via ls /dev/disk/by-label but was unsure how to mount it. (mount /dev/disk/by-label/CRUZER was my first try, that failed).
Since you probably have a desktop environment, and since that environment is probably similar to other windowing environments, you generally access USB drives via the left hand pane of your distros file explorer. (Nautilus is one example, Dolphin is another)