The fundamental difference between optical fiber and Ethernet cables is that optical fiber cables transmit data using light signals, while Ethernet cables transmit data using electrical signals. Ethernet cables, such as Cat5e, Cat6, and Cat6a, use copper wires to carry electrical signals, while fiber optic cables use thin strands of glass or plastic to. Fiber optic cable transmits data as pulses of light through glass strands and can carry terabits per second over many kilometers; ethernet copper cable is cheaper, powers devices over PoE, and handles everything in a typical home or office network. Optical signals are generated by light-emitting diodes (LEDs) or semiconductor laser tubes.