Kelley Blue Book Black Book
While both the Black Book and Kelly Blue Book provide pricing details regarding vehicles, the type of pricing is very different between the two.
Kelly Blue Book
The Kelly Blue Book, located at KBB.com, provides retail pricing on vehicles. This gives the average person an idea of what they would expect to pay when purchasing a vehicle. It gives you pricing based on three different criteria. Retail, which means what you would expect to pay at a dealership; Trade-In Value, which is what you would expect to see when trading the vehicle in for another one and Private Sale, what you would expect to pay if you purchased the vehicle through a private party.
While each of the three prices may be a little different, it gives an estimate as what you might pay for a vehicle.
These prices also take into consideration the condition of the vehicle. Depending on the condition, the price will adjust.
This "book" is consumer driven, with the intent to give the consumer a basis on pricing and automobile.
The Black Book
The Black Book, located at BlackBookUSA.com, is a book that compiles pricing of what a vehicle goes for at a private, dealer only auction or wholesale pricing. Dealers get better pricing at these auctions because they don't have to deal with the general public, or the consumer. This pricing is also reflective of the fact that there could be issues with the car, that don't have to be repaired by the selling dealer.
The vehicles sold at dealer-only auctions can be anything from a lemon to a "cream puff," or a "cookie cutter car;" a car with no problems and is consumer ready. Dealers don't usually have the benefit of inspecting the vehicle before they purchase.
This "book" is dealer driven; giving the dealer, or a consumer, information on what pricing is on the wholesale end. The information contained in this book, is not available to just everyone. Unlike KBB.com, you will need to subscribe before you can get any of the information it contains.
Another way to get similar information as contained in this book is to take a step in at the local dealer-only auction. Most of the time you can walk inside without having to show proof that you are a dealer, but you can't get into the actual "auction lanes." Most of the time, these auctions will produce their own books or leaflets. These books will contain information about the sales that took place the month before. It will list make and model with the actual selling price, not an estimate.
Though the two of these guides are similar, they are very different and serve two different purposes and the two ends of the auto buying business.
These "books" are not definitive with pricing; they are just a guide, or an estimate. Pricing could be very different than what is stated in these, but none the less will be at least vaguely similar.