East egg is old money, people who grew up with money, and West egg is new money, people who just got their money
West Egg is modeled after Great Neck, NY and was considered the "new money" area. East Egg represents "old money" and a more refined culture.
I am hoping you are referring to the Great Gatsby. The are is known as the Valley of Ashes, which is the industrial part of town.
east egg
It represents the newly rich, young ambitious people of Long Island Sound. Gatsby and Nick live here and new customs are being practiced, like lavish parties, drinking, and general ruckus.