Both dramas are makjang and about revenge. Both the female lead is an orphan and her older sister took care of her after the parent's death. Both the older sisters of the female lead is pregnant and being betrayed by their boyfriend. Both of older sisters dies with their child. Both the female lead wants to revenge on the person responsible of her older sister's suffering.
>Tae Jeong and Joo Da Hae are similar because they have greedy ambition
>Tae Jeong and Joo Da Hae have left their child to another woman/man
>Tae Jeong and Joo Da Hae's spouse are both naive
>Seon Yu is similar to Ha Ryu they both want to revenge the people who are responsible of the sibling's death
>Tae Jeong and Joo Da Hae have left their child to another woman/man
>Tae Jeong and Joo Da Hae's spouse are both naive
>Seon Yu is similar to Ha Ryu they both want to revenge the people who are responsible of the sibling's death
While one of the dramas is a revenge story and the other is just family-romance, in both female leads lied to male leads before the marriage and suffer after the marriage because they need to keep secrets from the people they love. You may hate the female leads for hurting their men, but still can understand their actions. *Wedding doesn't happen in the very beginning and you see the whole development of the relationship in both, from OTP's first encounter.