The cost per KC-767 is 19 million more per airframe than the Kc-30 was last round, around 3.4 billion more in upfront purchase costs.
The KC-767 won on a “factored” costs. The life cycle costs savings may or may not ever be realised, the RFP used a mix of sorties which is an average of how tankers were used in the past 20 years, however it is not representative of how they are used today with the high operational tempo of overseas deployments.
What "total life-time program cost differential" means is the purchase price was factored by hypothetical fuel usage, MILCON costs, and capability.
The fuel usage is where Boeing would have won, however that figure is distorted as currently tankers are being used at high operational tempo, and are doing less of the training as a percentage of their total flying. That was not reflected in the distribution of missions in the FURA analysis.
Their train set, they know best. The long term plan of the USAF is to retire all KC-135s and KC-10s, and just have a single fleet of tankers. This will be done in 3 phases, this is the first phase called KC-X, the next two phases are known as KC-Y and KC-Z.
Some facts, the unfactored purchase prices of KC-30 was cheaper per airframe , and also was deemed to be more capable in the air refuelling role than the KC-767. It was found for the USAF to get their planned tanker fleet strength (600 KC-135R equivalents), they would need to purchase 42 additional KC-767s.
The purchase of those additional 42 aircraft (with an upfront purchase price of 8.1 billion), and the additional fuel burn, maintenance costs, and MILCON costs were not factored in the RFP.