Coach
Original meaning and etymology
The original meaning of the term coach was: a horse-drawn vehicle designed for the conveyance of more than one passenger — and of mail — and covered for protection from the elements. The small Hungarian town of Kócs (pronounced approximately "coach") was the place of manufacture, from the 15th century onwards, of an exceptionally well designed example of such a vehicle with durable and comfortable suspension and steering; and from the Hungarian word Kócsi (meaning "from Kócs") the name spread to several other European languages (compare Spanish coche and German Kutsche).
Railway coach
A railway coach — also known, especially in the UK, as a railway carriage — is a vehicle designed for the conveyance of passengers by rail (the first such vehicles were, in fact, often road coaches mounted on frames equipped with railway wheels). In North America railway coaches are usually known as "railroad cars". A railway coach can be self-propelled such as the Budd Rail Diesel Car (in which case it is known as a railcar), form part of a multiple unit of self-propelled vehicles, or be pulled or pushed by one or more locomotives either singly or together with other such coaches. For more information on railway coaches, see the articles on railroad cars in general or passenger cars for more specifics.
Motor coach
In British English and Australian English, the term coach is also used to refer to a large motor vehicle for conveying passengers. It is similar to a bus but usually more comfortable and designed for longer-distance travel or touring. The term coach appears in the formal names of many such firms in the US, though most people still call them bus lines.
The main differences come from the facts that passengers of a motor coach are not considered potential vandals, and that a coach service is in competition with other means of long-distance travel. Thus most often coaches have upholstered seats, carry a toilet, and are air-conditioned. Fitments have come to resemble those of an airliner, with storage bins for carry-on luggage and individual lighting which enables passengers to sleep. There is even luggage storage below the floor, accessible from outside panels, just as in an airliner.
A bus also has has the differences resulting from having to take on and discharge many passengers for very short runs. They often have both front and rear doors, which open in an accordion fashion. There are more and larger untinted windows for passengers both standing and sitting to watch for their stop, and devices to alert the driver for this purpose. Buses also either carry a conductor or else have a fare bin near the driver. Many have advertisements both in the interior and on the outside. Coaches do not have these things.