I recently, for my birthday, got a 2016 Blue Book from a friend of mine. I noticed many differences, like a G-4 Common Indian Head Cent being worth $2.00 in Red and $0.80 in Blue, a G-4 1909-S V.D.B. worth $800 in red and $450 in Blue, and even the 1894-S dime, $1,500,000 in Red and $600,000 in Blue.
Why the differences? I noticed at the beginning that the Red Book lists the retail value of the coins, while the blue book lists the average price that coin dealers will pay. I decided to value my collection according to the blue book, and it turned up embarrassing results, as my collection was not even valued at $1,000. I recently started up my cmccs*coins, my eBay business. I have found the Blue book to be very useful in figuring out the price I should pay for coins that I am considering purchasing, and the Red Book helps me value the coins that I want to list on eBay.
For instance, the Blue Books lists average Very Fine Peace Dollars at $19-20, and I can cherrypick AU coins and get them for $19 apiece. The red book values the coins at $28-30, so I sell them at about $25 apiece. I buy a roll of 20 for $380 and sell them for $500, the fees and shipping bring the price down to approximately $410, a $30.00 gain.
I love the Blue Book!!!