In both dramas a sibling of one lead killed a sibling of the other lead.
Seredemo, Ikite Yuku plot:
Fukami Hiroki's younger sister was killed by a friend. Hiroki then meets the killer's sister, Toyama Futaba, 15 years after the incident. Both of their families have been burdened with grief, but through their meeting they struggle to find a brighter tomorrow.

Both dramas explore the time-traveling concept, have romance and crime. They have the same vibe. Both are quite dark, but have funny and cute moments as well. Both very touching.

These two dramas are really similar, especially the female leads. They are both single mothers and male leads fall in love with them despite of everything. I am sure that if you liked one of these dramas you'd like the other one too.

The plot is a bit similar (not too much), but overall mood is very-very similar. If you'd liked one of these dramas I'd bet you'd enjoy another.

They have many similarities: overall mood, broadcasting station setting, dramatic siblings stories, etc.

The main characters are similar, they are both psychopaths and can't feel complex emotions but try to imitate them to blend in the society.

Both dramas show the similar stories of growth of the female leads, and in both the female lead and the evil second female lead work in the same company, which belongs or belonged to the female lead's family. Both the female lead and the evil one are sisters in some sense (not by blood, but you will understand what I mean while watching).

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.

Similar stories with two girls from different backgrounds changing identities. A girl from a wealthy family loses her memory while another one consciously deceives everyone. Male lead and female lead met in childhood. Male leads in both are great (their characters).

Twinkle Twinkle is about a reversal in lives of two families when they find out that their children were swapped after birth. Similarity with My daughter Geum Sa Wol lies in the jealous behavior of one of the women and some family issues.

The relationship between the main leads is similar. The girl is kind of obsessed with the guy and he starts to develop feelings for her.