Nick Carraway is the moral compass and narrator in Gatsby. While he comes from respected family, he is determined to make his own way in the social world, as well as the business world. He lives in West Egg, yet has the social clout to live in East Egg.
Tom Buchanan is "old money". The ex-golden boy who relies on his inherited social standing to maintain his respectability. He cheats on his wife, is a blatant bigot, and never possessed an ounce of integrity.
Daisy Buchanan lives the dream life, as Tom's wife, yet is disillusioned with the reality of marriage, and the plight of a woman. She is shallow, yet vulnerable.
Jay Gatsby, is a man desperate to appear to be a man of culture and class.While he has accumulated wealth-his house, cars, and clothes are seen as tacky. He emulates those he decides are the models of who he wants to be.
Nick is well-off, but not part of the wealthy social class that Gatsby, Tom and Daisy belong to. Tom and Daisy have always been very wealthy, and thus their personalities are shaped by it. Tom is loud and his morals are all biased from being wealthy. He is brash and uncaring towards others. Nick on the other hand, is the moral center of the novel. He withholds jugdement from others and tries to do the right thing. Gatsby, is just trying to fit in with the wealthy that he has become. His personality is clearly one of determination (chasing Daisy all of those years) yet he is also a pretender, he fakes being who he is to get into Daisy's society.
As to social status: Nick is a striver; Gatsby a striver but deceiver; Tom, an elitist snob; Daisy, undeniably upper class but more egalitarian than her husband. Each character's lifestyle is to a great extent driven by her/his status: Nick perseveres the West End in order to enter the graciousness of the East; Gatsby displays the flambouyance he believes to be appropriately associated with the upper class; Tom and Daisy indulge in the indolence and amusement only real and old money can buy, although sadly those commodities seem to be all that are available to them despite all their good fortune.