It's all in the resolution, DG. 'HD Ready' is usually up to 720p resolution (1280×720), whereas Full HD is 1080p resolution (1920×1080). An 'HD Ready' set will usually accept the higher resolution input from, say, a Bluray player, but will downscale the output to it's native resolution, which, I think, to be precise, is usually 1366x768. A 'Full HD' set will display the picture at the full 1920x1080 resolution, hence, theoretically, a sharper image.