Is there a difference between FireWire 800 and 1394b?

Only in vocabulary. those are two different ways identifying the new second FireWire standard, as defined by the IEEE and bringing FireWire to a whole new level beginning in Summer of 2003. The new faster 800Mbps standard is called 1394b, FireWire 800 or just FireWire B, depending on who you talk to. Macintosh computer users tend to call it "FireWire" (Since Apple invented it), while Windows users and others think "1394". Our cables are popular with FireWire users on every platform, so we speak both languages.