Wiring diagrams

The difference between a schematic diagram and a wiring diagram is the amount of detail included. In a schematic diagram, the interconnection of the components is shown, but the actual values of the components are not necessarily indicated.
You might see a diagram of a two-transistor audio amplifier, for example, with resistors and capacitors and coils and transistors, but without any data concerning the values or ratings of the components. This is a schematic diagram, but not a true wiring diagram. It gives the scheme for the circuit, but you can’t wire the circuit and make it work, because there isn’t enough information.
Suppose you want to build the circuit. You go to an electronics store to get the parts. What sizes of resistors should you buy? How about capacitors? What type of transistor will work best? Do you need to wind the coils yourself, or can you get them ready made? Are there test points or other special terminals that should be installed for the benefit of the technicians who might have to repair the amplifier? How many watts should the potentiometers be able to handle? All these things are indicated in a wiring diagram, a jazzed-up schematic. You might have seen this kind of diagram in the back of the instruction manual for a hi-fi amp or an FM stereo tuner or a television set. Wiring diagrams are especially useful and necessary when you must service or repair an electronic device.