Fitzgerald has used East Egg and West Egg to represent old wealth and prestige versus new money and bourgeoisie. The people in East Egg, such as the Buchanans, have come from families who have always had money; they have been well educated at Ivy League colleges such as Yale. Those in West Egg, on the other hand, like Gatsby, are newcomers. They don't come from wealthy backgrounds; rather, they have made their own fortunes. Instead of Ivy League college degrees, people in West Egg are more likely to have work experience gained while they made their money. The people here tend to build ostentatious houses; Gatsby's is unbelievably huge, luxuriously furnished and decorated.
Generally speaking, those in East Egg look down on the people in West Egg as brash newcomers. Fitzgerald reinforces the contrast with the difference in values between those who live in the American East and the Midwest. Although Nick Carraway, a native of the Midwest, lives in West Egg, he merely rents a cottage. Daisy's cousin, Nick is more like those in East Egg because of his background, but he chooses to live in West Egg because he's trying to make it in the bond business and doesn't have much money of his own. The East Egg citizens are portrayed as corrupt and jaded while those in West Egg are seen are less sophisticated, more innocent.