The IEEE 1394 interface is a serial bus interface standard for high-speed communications and isochronous real-time data transfer, frequently used by personal computers, as well as in digital audio, video, automotive, and aeronautics applications. Apple calls theirs Fire Wire, Sony calls it iLink & Texas Instruments calls it Lynx.
USB and firewire are different interfaces. Hi-Speed USB 2.0 is a 480 Mbps interface and FireWire is a 400 Mbps interface.
Take a look @ this - howstuffworks.com