One way to know for sure(you can even do this with any shielded
cable):
#1 Remove the female ends on the cables you want to compare
#2 Before plugging the male end into a normal wall socket or dedicated line,have a friend insert the male end into the receptacle for you while you hold the bare end.
Hopefully he has the male end right at the receptacle so insertion would be a split second at most.
By trying this,I doubt if you can tell which cable is faster.