I don't think that sony digital 8 camcorder have a firewire port on them. I think that only the miniDV camcorders have a firewire (or DV in/out, iLink, as they are sometimes called).
The 4w-4w is a cable with 2 small ends on.
The 4w-6w is a cable with a small plug on one end and a larger (near USB size) plug on the other end.
Normally a firewire card in your computer has a 6w socket and a camcorder has a 4w.
If your camcorder does have a small socket for the firewire then you would need the 4/6 cable.