Inside your vehicle, beneath the instrument panel, there is a unit referred to by different names depending on the vehicle manufacturer, but often referred to by the generic names “the plenum assembly” or “the case/duct assembly.”
The expansion valve’s place in the system is at the evaporator inlet. Like any other valve, its job is to control flow; in this case, the amount of refrigerant entering the evaporator.
Receiver/driers (also sometimes called “filter/driers” or “receiver/dehydrators”) look like small metal cans with an inlet and outlet. They are only used in A/C systems that use expansion valves.
The evaporator, also sometimes referred to as the evaporator core, is one of the two (maybe three) heat exchangers in a mobile A/C system. In a typical passenger car or pickup truck, the evaporator is usually located inside the passenger compartment, quite often deeply buried in or under the instrument panel.
The condenser is the other heat exchanger in a mobile A/C system. Nowadays, condensers are usually made of aluminum, but in the past, some were made of copper/brass. Condensers look very much like radiators, just a little thinner, and since they also depend on air flowing through them, are usually located in front of the radiator.