cat 6 cabling is more insulated and thus capable of more diverse implementations environments and higher data speed transmissions. cat 5 ran at around 200mhz and cat 6 is around 500. the ends CAN be different, most cat6 ends are staggered with 1 and a half rows of wires vs cat5 which has a single row and all wires on an even plane. My experience is that standard cat5 ends will fit cat6 but they will be very tight to get on. the preferred cable wiring is white orange, orange, white green, blue, white blue green, what brown, brown. this is the tia B standard which the vast majority of equipment is wired for and all corporate holds as its standards.