Uh? They're trivial to tell apart, just put the RJ45 jacks side by side and look at the colors of the wires going in? Same sequence -> Straight ethernet cable

Uh? They're trivial to tell apart, just put the RJ45 jacks side by side and look at the colors of the wires going in? Same sequence -> Straight ethernet cable Same sequence except for 1 swapped pair -> Probably a crossover Ethernet cable Inverted sequence -> ISDN cable, burn it. Also (apart from the ISDN cables) - it hasn't mattered for close to quarter of a century, all switches and NICs are auto-MDI-X nowadays, why throw away the stuff.