I suppose that nerds have been made into some sort of positive symbol, quite the opposite effect of many years before. (I believe the movie, Revenge of the Nerds, aided in some measure.)
Nerds can be defined nowadays by a ridiculously trivial knowledge of one certain intellectual pursuit or another - whether that be chess, punk rock, or the academic subjects. That differs from an athletic pursuit, for that belongs to the jocks. And that also differs from the aesthete, for the artist is not 'smart' enough to be a nerd, but not strong enough to be a jock.
I'm merely speaking from the many generalizations given in high school society, and high school TV shows/movies.