Luca: fwiw, "disc" is used for media which is a flat disc (i.e. CD/DVD). "disk" is used for everything else (even though they often contain flat discs, such as floppy disks and hard disks do). It's certainly true that USB memory sticks/disks are often called "thumb drives", but they should never be called "discs".
Luca: fwiw, "disc" is used for media which is a flat disc (i.e. CD/DVD). "disk" is used for everything else (even though they often contain flat discs, such as floppy disks and hard disks do). It's certainly true that USB memory sticks/disks are often called "thumb drives", but they should never be called "discs".