In this case, refers to the type of non-volatile flash memory used to store your data. USB2Disk signifies the controller chip that bridges the NAND memory chip to your computer's USB 2.0 port.
The NAND USB2Disk device is a legacy mass storage controller. It acts as a bridge between your computer's USB port and the raw NAND flash memory chips inside a device. nand usb2disk usb device driver