What are the differences between USB Boot and CD/DVD Boot. I am confused when booting from USB. My BİOS setting is set up for Legacy Mode and USB Boot but now something is different from CD/DVD boot. In DVD boot we restart PC it gives a notification at the start as push a key. Without logging in we can do the installation. But in USB case, I don't take any notification. After loggin in, under my computer I access to the setup file in the USB. The I start installation. Is this normal? Should it have been like in the case of DVD boot i.e not logging in?