Two shapes are common. One operator runs several delivery-only brands out of a single kitchen, splitting one line across menus that look like separate restaurants online. Or a host fits out a building with individual production units and rents them to separate brands, each handing off to couriers from the same door.
The distinction from a commissary is what each word describes. A commissary is defined by who may use the room; a ghost kitchen by how the food reaches the customer. A ghost kitchen can run out of a rented commissary, out of a restaurant’s spare capacity, or out of its own unit. Cooking for delivery only does not exempt a space from the permitting rules that apply to it — confirm what yours needs with the authority that issues your permit.
The economics trade one cost for another: no dining room means no front-of-house rent or staff, but delivery commissions, packaging and the cost of being invisible — there is no passing trade and no room in which to build a reputation. Many operators test a delivery brand in rented kitchen time before committing to a unit of their own.

