T568A and T568B are the two color codes used for wiring eight-position RJ45 modular plugs.  Both are allowed under the ANSI/TIA/EIA wiring standards.  The only difference between the two color codes is that the orange and green pairs are interchanged.     T568A wiring pattern is recognized as the preferred wiring pattern for this standard because it provides backward compatibility to both one pair and two pair USOC wiring schemes.   ... T568A and T568B are the two color codes used for wiring eight-position RJ45 modular plugs.  Both are allowed under the ANSI/TIA/EIA wiring standards.  The only difference between the two color codes is that the orange and green pairs are interchanged.     T568A wiring pattern is recognized as the preferred wiring pattern for this standard because it provides backward compatibility to both one pair and two pair USOC wiring schemes.   ...