Compare and contrast Miss Emily & Grace Ansley: both are deceitful, passionate, upper class women; I can't find the "contrast" part.
"A Rose for Emily" is the first story, and Miss Emily is the main character. The other story is "Roman Fever" and Grace Ansley is a major character.
Looking at "A Rose for Miss Emily" by William Faulker and "Roman Fever" by Edith Wharton, your assessment in terms of a comparison is correct: both Emily and Grace have harbored a secret for many years. (I don't know if I would call Grace "deceitful;" if she had lied to her husband, perhaps this would be the case, but we don't know.) "Passionate" and member of the upper class also apply to both women. Additionally, both womn are not just secretive, but they harbor secrets that would shock society at large. These are ways in which the two women are the same.
In contrast, Emily and Grace come from very different parts of the country. Emily is from the South and Grace is from the North. Miss Emily forced Homer Baron to "stay with her" by killing him. It is possible that Grace could have made things very difficult for Delphin in that she carried his child, but she marries another man and remains silent, protecting both her child, Delphin and his marriage, and herself, obviously.
Another difference between the two is that except for the murder, Miss Emily has no problem defying society. She lives alone—without a female chaperone—after her father dies, she goes out in public with a man beneath her social station, and she adheres (or not) to local laws as she sees fit. On the other hand, Grace is a good wife and mother. She has never spoken of Delphin's parentage to her child, but harbors the secret of their time together in a very sentimental way. (Rose seems sentimental about nothing; she's just twisted.)
Finally, Rose never shares her secret, taking it to her grave. However, when Mrs. Slade (Alida) reveals that she wrote the letter that Grace thought Delphin had sent her, Grace finally reveals her secret, almost in self-defense. As Mrs. Slade tries to hurt Grace and rub her nose in the fact that she had her husband (Delphin) for many years: Grace "trumps" Mrs. Slade's play by revealing that she had Delphin's child.