Both are tragic palace dramas about yearning/forbidden love. The dramas are well acted and have great OSTs. I also enjoyed the bond between everyone at the palace (TRS) and the friendship between the generals in One and Only.

Fl crushes/likes a guy in high school and reunites with him later. It deals with the same themes~ unrequited love, misunderstandings, fl chasing ml...etc.

Both explore what it means to be a family and explores sibling relationships, abandonment, and mental health issues.

It's the same type of webtoon humor following ridiculous adventures. It's also slice of life and centered around familial relationships.

The heroine also time travels to the past through a mirror and falls in love with a man in the past.

Both dramas are slice of life Cdramas about young girls who share an apartment/dorm and bond over the sorrows and successes of love and life. Somewhere Only We Know is more college centered and has more romance.