In both series the main female has electricity run through her and the male lead accepts and helps her along the way.

In both series the female lead finds out that she is sick and ends up in a relationship with a total stranger.

In both movies, after an accident the main heroine 's life gets changed. Both try to cope with their new life and we have ridiculous moments.

In both series after an accident the main girl believes she's a high school student.
Also her main interest tries to make her regain her memories.

In both series the main characters go back in time and they end up finding love when/ where they least expect it.

The ambition of a man who would do anything for money. In both series the main character tries to seduce a rich girl.

I feel like the main lead's characters are quite similar..also the plot for both series has similar themes as well..sudden death, the desire to gain power, manipulation of others, narcissism, naive women, etc.

Going back in time to change some moments and get the woman they want before she's "stolen" by another guy.

In both series the men find out after a few years that they have a child, the family doesn't like the mother and try to steal the baby. Both show the parents having other partners, both take a feminist path.

About the life of former idol girls..how they fare after they're not in the spotlight anymore.

Both are about daughter-in-laws that can't seem to cope with the strict life of their husbands and have conflicts with their new family members.

Similar plot..in both series the main leads end up living together because of some circumstances ; one of them can't stand the other one; both series start with "a letter of love", both girls are naive when it comes to love, etc.