Wires, cables, and cords are used to bring electricity from the power source to the item needing the power. The most common type of wire used in homes is copper or tinned copper wire because of its minimum resistance to conducting electricity and its affordability. All wires have gauge numbers - the smaller the number, the thicker the wire. And the thicker the wire, the more electricity flows through. There are also two wire types - NM and UF. NM wires are used for standard household wiring applications. UF wires are specially coated for use in outside applications, where they might be exposed to the elements. All wires are clearly labeled on the outside with the gauge and type.
Here are just a few wiring applications and suggested gauges. When wiring a doorbell or thermostat - use a 24 gauge wire. For overhead lighting fixtures, outlets, and switches - a 14 or 12 gauge wire is recommended. And for wiring larger appliances such as water heaters, and stoves - 10, 8, or 6 gauge wire is recommended. Follow the recommendations of appliance manufacturer and local electrical codes.
A cable contains multiple wires. Two conductor cables contain two wires and are capable of delivering 110 volts of electricity. Three conductor cables contain three wires and are capable of delivering 110 volts or 220 volts of electricity. A third type of cable is thermostat cable which is used when wiring alarm and communication systems. All thermostat cable is low voltage but does have an Underwriters' Laboratory or UL safety listing for flame retardancy - since it's installed in walls. Cables, like wires, also have NM and UF types.
Electrical cords deliver electricity from a fixed outlet to an appliance. The most common types of cords are extension, appliance, range, and dryer cords. Cord should reach easily from the wall outlet to the appliance and you never want to put two short cords together to obtain the right length.