Driveaway is a way of moving a vehicle in which a driver physically drives it from origin to destination. Dealers use it for short dealer-to-dealer moves, fleets use it to relocate vehicles, and it shows up in some commercial and new-vehicle delivery work.
The tradeoffs are simple. Driveaway needs no loading equipment and can be quick for one vehicle over a short distance. It also adds miles, wear and exposure to road hazards, and the vehicle has to be road-legal, properly registered or plated, insured and mechanically sound. That rules it out for any inoperable vehicle and makes it a poor fit for most retail deliveries to buyers who care about the odometer reading.
For most dealer, auction and marketplace shipments, trailer transport on an open car carrier or a single-car hauler is the norm, because the vehicle arrives without added mileage or wear.
If a move calls for driveaway rather than trailer transport, say so before booking, since the two are priced and handled differently. For a typical sale to a remote buyer, a trailered shipment keeps the car in the same condition and with the same mileage that the listing described.