There are three key differences between a wire and cable: 1) A wire is a single conductor, while a cable contains two or more insulated conductors. 2) There are two types of wires - solid and stranded - which have different flexibility and resistance properties.

In essence, cables are made up of multiple wires, while wires are made up of one or multiple conductors. Both can have a wide range of purposes, with wires providing the backbone for a vast range of cables that go in everything from appliances to buildings to heavy machinery.

When we think of Romex, we most commonly are referring to the trade name for Thermoplastic-Sheathed Cable (TPS). Romex is often used as residential wiring for electrical circuits and lighting. We generally think of a specific type of Romex, which is known for its nonmetallic sheathing and primary use as branch wiring.

It defines a cable as two or more wires bonded, twisted, or braided together. The main types discussed are: single core cable, 2 core cable, 3 core cable, 3.5 core cable, 4 core cable, armoured cable, and unarmoured cable. Each type is defined in terms of the number of conductors and common applications.