By AMD's own verbatim, these are units shipped by Sony and MS ("our customers") to retailers ("end users"). Sony and MS only ship directly to final purchasers from their own stores, which is the vast minority of sales, and it makes no sense that AMD would know the sales data of their customer's customers. I work with chip suppliers, and they only ever ask what we will need and sell us the lot (We have to put the order in up front.). To build on that, Sony has publicly stated sell through to end users (us) for Q4Y14, but MS has not. MS has announced shipment numbers quite consistently, however, so the only logical conclusion I can draw is that this is a reference to shipments from MS and Sony to distributors.
If I had to guess, AMD was originally talking about shipped to retailer units, but was scolded by Microsoft, because that data could reveal that Xbone sales are lower than 9 million. Better for people to think they're at 11 million than at 9 million.
That response from AMD was just damage-control without lying about sales. Even with sold-through numbers, the numbers would be close to 30 million.