I have an Asrock 990FX Extreme 4 motherboard with a UEFI BIOS. When I go into the boot menu with removable drives plugged in I notice there are two references to the drivers. If it is a flash drive it will have both UEFI: Name of flash drive and it will have USB: Name of flash drive. If I select UEFI: Drive the BIOS boots to the drive it is currently set to boot from. If I select USB: Drive name the BIOS will boot from that drive. What is the purpose of the UEFI: Drive name reference?

In an effort to find this out for myself I consulted my owners manual but it did not mention UEFI referenced drives. I email Asrock support but I did not get my question answered. Finally I did an Internet search but I did not find an answer to my question. Any information would be appreciated.