The total product concept - sometime called Levitt's rings relates to the fact that a product has several different dimensions.
The core product must address the basic need - a car must get you from A to B, however a bicycle or a train can get do this also. So the actual product is the car or the product form. But the total product is everything that the customer recieves - including the service and intangible associations such as Branding and percieved values associated to the brand.
Finally there is always the Potential Product - what the product could be.
This concept is developed from Theodore Levitt's articles in the Harvard Business review - "Marketing Myopia" and "The differentiation of almost anything."