Nothing, but it's a silly thing to argue about with respect to Verizon's marketing. They're not recompressing it, so it's uncompressed... by them. I doubt many people in the world have ever seen a truly uncompressed HD stream with their own eyes, so picking on this particular example of marketingspeak seems like a waste of time.

See also, arguments about the number of HD channels each carrier has... The lying there is even worse.