In fact there once was a difference between USB 1 & 2 cables: to comply with FCC regulations, the second ones had to be shielded (USB 1 were not). Thus USB 2 cables were (and still are) often made with a transparent/translucent outer envelope to let the shelding be visible.
Now non-shielded USB cables are not manufactured any more and all cables are up to rev.2.
Btw. do note that this shielding doesn't make the cable be faster than a non-shielded one; it's only supposed to stop any RF disturbance in order "... to comply with the FCC regulation #blahblahblah". 
And yes, CDS is right: don't waste your money in purchasing expensive "high-speed USB2" cables: they all are, the only difference is that sellers may be (or ain't) crooks. 