The only reason I caught those differences is because there was some debate at my agency as to whether a Limited Source(s) Justification should be labeled a "Limited Source Justification" or "Limited Sources Justification". Yeah, I know it is minor, and there are much bigger things to worry about, but it was just something that came up one day, and I discovered the difference between the two websites. It does make you wonder if there are other differences however, and if maybe they may be more significant. I know of no one who uses the acquisition.gov website for FAR research, and everyone I know uses the Air Force site. Even when I went to DAU training, they gave us the reference to the Air Force site.