Daisy Buchanan is not innocent, but she makes every effort to appear innocent. In fact, Daisy Buchanan is downright guilty, even murderous. After committing a fatal hit and run, she sacrifices Gatsby in order to retain her innocence -- and her enormous wealth. By contrast, Daisy Miller's innocence is far more pure, natural, and unprotected; certainly, Daisy Miller never kills anyone knowingly only to plan and execute a cowardly escape that sacrifices an innocent man. Daisy Miller does not pretend to be a forthright flirt; she doesn't need to. She simply is. She acts honestly and exactly as she wishes with Winterbourne. Daisy Buchanan, on the other hand, is hardly convincing when she puts forth the visible effort to be the innocent flirt she claims she once was. In short, Daisy Buchanan is guilty, cynical, world-weary, surprisingly wise, oppressed, pessimistic, 'fake', and jaded. Daisy Miller is optimistic, energetic, eager, fresh, new, young, and surprisingly untouched by a world that seeks to limit her. Daisy Miller is more innocent, open, and simple than Gatsby's Daisy ever was -- even back in her imaged idyll, her "glorious white youth," in Louisville.
In The Great Gatsby, Daisy Buchanan begins happy in her marriage to Tom Buchanan, but after she discovers his infidelities, she withdraws into a dream world. She does however have an interest in Jay Gatsby During the interim, she meets Tom Buchanan and marries him. At first happy in this marriage, she later discovers that Tom is having affairs. She withdraws into a dream world, yet never loses interest in the illusion of her love with Gatsby. Daisy flirts with him and entertains his obsessive interest until she commits murder and he takes the rap. Then, she hides behind the protection of her husband, a cruel brute, who uses and abuses people. Moreover, Daisy's voice is the voice of money, as Nick discovers. Her whole careless world revolves around this illusion: that money makes everything beautiful, even if it is not. In short, she hides behind her money and the men in her life to protect here.
On the other hand, Daisy Miller is direct, independent and somewhat presumptuous. She is charming and somewhat foolish; she demands independence but wants social approval; she is victimized but also contributes to her unfortunate destiny.