To expand a little on Ron's list, a coach is the part of the motorhome built by the coach works, ie, the motorhome manufacturer, such as Winnebago or Phoenix. It does not include the chassis, nor the cab on C class units with a cab manufactured by the chassis manufacturer, such as Ford, Toyota, etc. Your coach is the big box mounted on that Toyota cab and chassis.
At least thats my definition and I use it to differentiate between the coach and the chassis, usually in discussions about who manufactured or equipped the motorhome with a particular item of feature. Batteries are a good example. There is a CHASSIS battery, that is used to start the engine, etc, just like the batt in your car. Then there are COACH or HOUSE batteries, that power the lighting, fans, water pump, etc, in the coach part of the vehicle.
Charles
'03 Ram 2500 CTD, 5.9HO six speed, PacBrake Exh Brake, std cab, long bed, Leer top and 2008 Bigfoot 25B21RB.. previously (both gone) 2008 Thor/Dutchman Freedom Spirit 180 & 2007 Winnebago View 23H Motorhome.