Ethernet cable, sending and receiving each bear a pair of twisted, for the two devices are connected, in order to send and receive correspondence in order to work properly.
Ordinary Ethernet cable is used to usb 3.0 connector straight, two are exactly the same. Generally connected (such as switches and computer) between the network device and the terminal device, exactly as they are defined in turn the transceiver.
crossover ethernet cable is optical fiber cable cross the line, two are cross-connected. For connections between similar devices (such as computers connected to the computer, switch connected switches, etc.), because they are the same as defined transceiver, using a crossover cable so that it corresponds to the transceiver.
But now there are many devices to send and receive automatic reverse function, in most cases you can use the direct connection.