GT:HD was originally split into two games GT:HD classic, a marked up version of GT4 running at high resolution with larger car grids ect. And GT:HD Premium, a kind of GT5 Prologue if you will, GT:HD classic and Premium were originally intended to be sold as a game in the shops, but GT:HD classic was scrapped and GT:HD Premium became GT:HD concept, which is a demo. GT5 is the next GT game in the GT series, GT:HD is currently just demo material. And a real GT5 Prologue is slated for release later this year. Also through the year you may see newer versions of GT:HD being talked about and released as free downloads. It can be rather confusing, look at GT:HD as early demos of GT5, with many features not present or subject to change.