Think about the difference between playing a record and a CD . 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.