Even with a superbly mastered and reproduced album, that analog recording takes a beating over time, due to scratches, nicks and wear. A CD recording generally doesn't. A similar effect applies to the shift from analog to digital TV broadcasting. Resolution is the number of colored dots used to make up a picture. More lines translate into a sharper picture.
Resolution is only part of the story, though.
HDTV can draw the lines in one pass , delivering a sharper, flicker-free picture. It's the broadcasters' decision. Both look better than analog pictures, and virtually every HDTV can handle either format. It has been formatted to fit your television screen. On standard TV the alternative is letterboxing, which runs the movie's entire width, but adds black bars at the top and bottom.