The north is colder, so Northern Preps tend to wear more clothes (e.g. navy blue blazers, Natucket reds, Aran sweaters, boat shoes). Southern Preps wear lightweight clothes, often in white, to deal with the greater humidity (e.g. seersucker blazers, linen slacks, and straw hats)

Weather and accent. Slow moving style, because it's a beautiful day, bound to make you smile. In the North when it's cold, it's hurry, hurry, huddle under layers, trying not to frown.