USB cabling is shielded, either with foil, braid, or both (I have two clear cables, and they are braided, another where the sheild is just wrapped around.
1394 is different. It has two pairs for data (USB has one pair), but optionally has power (there are 4 and 6 way connectors and cables)
AFAIK, for both USB and 1394 it is 5V power .
