=> action packed historical kdramas
=> two rival men and there is a woman loved by both men. one man is connected to the woman's past, the other one is the one she is currently serving/following

=> Both are historical dramas where a mother is the main character
=> They may not have many similarities but both shows have a similar theme: to what extent parents can do for their children. Both dramas depict the good and evil in parents.

Both are fantasy kdramas where actor Lee Tae Ri plays an interesting character in both. Both have bits of Goryeo era in the show.

=> Adult characters reminisce about their youth and first love when they were teenagers in the 1990s
=> There is a sad event in both shows that will make viewers think about the show for weeks
=> Female leads are played by two amazing former child actresses considered rivals by many (Kim Yoo Jung and Kim So Hyun)

Both are historical films featuring intimate scenes between two people of the same gender. The acting is also amazing in both. Song Ji Hyo in Frozen Flower has strong presence.

Both sageuk films that feature intense relationships. both films have some scenes not for minors too. Homosexuality is featured in both.

=> We see in Scholar Walks at Night episode 17 that Lee Joon Gi acts as 3 characters meeting. In Arthdal, fans are waiting for Eunseom Saya meeting. You can use LJG Scholar Walks at Night scene to see how he will act the meeting scene of Eunseom and Saya in Arthdal.

=> Both dramas depict how the North South Korea divide affects and separates people
---> in CLOY, it's the couples being separated and cannot be physically together for a long time
---> in Curtain Call, the grandma is separated from her first original family from North Korea
=> Female lead is a CEO in both dramas and Choi Dae Hoon is playing the brother of the female leads in both dramas.
=> Though male lead in Curtain Call is South Korean, he is pretending to be a North Korean character so that North Korean aspect of him makes him similar to the North Korean male lead in CLOY. Curtain Call male lead is also an actor and he plays North Korean characters in his plays, one time even mentioning Hyun Bin (CLOY actor)
=> Bonus: Female lead Ha Ji Won once worked with Hyun Bin in Secret Garden

=> 1990s setting
=> we begin and end the show with the adult versions of the female leads
=> very active female lead who loves sports
=> focuses on both the friendships and the romantic experiences of the female lead
=> two female leads shown as often chatting each other on the computer
=> most likely the audience will have a similar reaction in how the main love story in both dramas fold out
=> main difference is that there is no love triangle in 2521 while there is in 20th century girl

=> Both are Song Joong Ki dramas, both are about revenge. The people SJK is doing a revenge against are very rich/high on the social ladder (at least during the time SJK character is doing the revenge). SJK did fantastic acting in The Innocent Man, here's hoping Reborn Rich has enough where SJK can show his acting ability.

Both dramas tell the story of King Sukjong and his wives from totally different sides/perspectives. Royal Consort Choi's side is told on Dong Yi while Royal Consort Jang's side is told in Jang Ok Jung.

=> Both are dramas set in Three Kingdoms of Korea
=> Both main characters eventually became rulers
=> Both main characters were born with a bad omen, thus they had to live away from the palace in order to be not killed
=> Both main characters returned to claim their title as prince/princess when they got older.
=> Both main characters have an older sibling that loves and protects them