In some of the literature on Fitzgerald, "Winter Dreams" is cited as a "draft" of what became Gatsby. The parallels between Dexter and Gatsby and those between Judy and Daisy are certainly present. Some of the color motifs are shared, although they are fairly consistent in much of Fitzgerald's work. White, silver, and gold are associated with wealth and the privileged class. There are many references to all three colors in both works. Interestingly, when Fitzgerald met Zelda Sayre in Montgomery, she drove a little white roadster.
I disagree with the answer above in regard to Dexter. While he does have a distinct disadvantage over Gatsby in that he, at least, remains alive, for all intents and purposes, Dexter is dead. Notice the way the colors change...in the beginning, of course, everything is cold and white. Virginal. As Dexter becomes closer to obtaining what the "thinks" is his desire, the colors become warm and golden. But in the end, his world is devoid of color. No longer virginal, no longer white, Dexter's physical world reflects his mental state: grey and lifeless. Though he lives, his life is over.
FSF's work is often very autobiographical. Judy, and later, Daisy, is based very closely on a woman who ditched the author early on, Generva King. Fitzgerald's insecurities would not improve on meeting Zelda. Zelda, like Judy, and Daisy, was of a much higher social standing than himself. He never quite got over the initial snubbings from her well-heeled circles.
As an aside, FSF once whined to Hemingway, "The rich are different than you and me." Hemingway famously quipped, "Yes, they have more money." Fitzgerald was never quite convinced of this fact; throughout his life, he longed for the magical quality he thought the rich possessed, even though time and again, like Dexter, the rich would only sorely disappoint him.
If you are writing a paper on this topic, you might find it helpful to visit our page here at eNotes, How to Write a Compare and Contrast Essay.
Both stories are seem similar at first because they are both about poor young men who fall in love with rich, unattainable, women. Both women lack real values yet both Jay Gatsby and Dexter Green live their lives and attain success in order to win their love. However, Gatsby goes much farther in his pursuit of Daisy Buchanan than Dexter goes in his quest for Judy Jones. Gatsby changes his entire identity, makes up stories about his past. and gets his money through mostly illegal means. Dexter, on the other hand, attends an excellent university and makes his fortune as a successful businessman. He is able to return to his home town and is invited to meet with men for whom he used to caddy. Then he learns that Judy's "beauty and vitality have faded" and he feels empty. But at least he is still young and most importantly, alive. He can still learn from his experience. Gatsby, on the other hand, sacrifices his life for a woman who will never truly appreciate what he has done.