A caravan is usually a home or living space attached to a trailer. This means a caravan requires another vehicle such as a ute or larger car to be mobile. Caravans are joined to motor vehicles via a towing connection.
With campervans (or motorhomes) the living space is part of the vehicle itself. Usually the interior of a van or larger vehicle has been fitted out for living and sleeping. This means campervans are fully mobile and do not require another vehicle to transport them.