I think of two kinds of preppies. They both usually share being rich and snobby.
1] Generally slutty-guys and girls, rich, but still probably attends a public school, skanky, wears
Hollister, A&F, Aeropostale, American Eagle, etc,
blonde, spoiled, easy, usually snobby, annoying, giggly, does stupid things sometimes nice, "popular", but really not.
2] Goes to prep school. Wears cardigans, corny, VERY RICH, very annoying, smart, sheltered,
parents often ignorant of behavior...
1]
Meg is such a preppy-she wears
Hollister, she's a snob, she's rich...
2] Muffy is such a prep-snobby, very rich, sheltered,
corny, and dresses bad.