The King's Affection (2021)

In both dramas, the girl acts or "becomes" a man.
In both dramas are historical
In both dramas, the girl acts like a man because of their brother

Both are historical dramas.
The female lead pretends to be a eunuch (disguised herself as a man).

- ML in The Tale Of Nokdu and FL in The King's Affection, both hide their real idendity
- both also end up falling in love

If you like historical dramas where the royals hide secrets and a romantic love story between the main characters, this would be of interest.

The queen in both dramas plays a part in coordinating the chaos in the palace.

Both dramas have a good sense of humor.

SIMILARITIES
- The main character (MC) who grew up a commoner at first is a fill in for the king, as per the king's request
- MC ends up needing to become the king when the real one *spoiler* inevitably dies to prevent political upheaval and many deaths
- There's a romance plot line
- Both dramas have good acting and cinematography

DIFFERENCES
- In TKA the king and MC are twins, in TCC they're just look a-likes
- TKA follows a female MC and in TCC it's a male MC

Both have childhood connections with tragic pasts and siblings dying. Both have a similar looks and feel with a balance of heart stomping loss and grief and light comic moments. Familiar palace characters In both.

*In both dramas, there is a power difference between the ML and the FL. *

MAIN PLOT:
-In The Red Sleeve there is love between crown prince (ML) and a court maid (FL).
-In The King's Affection it's the opposite. The FL is disguised as a man and she is also the crown prince who is loved by the royal tutor, who is our ML.

SIMILAR TOPICS OF:
-Childhood nostalgia
-Difficult and abusive family relationships
-Political drama
-Injustice in Joseon; class problems and gender inequality
-Love between people from different classes.
-Multidimensional characters with their own ambitions.
(All of these topics affect the relationship of the FL and ML. )

DIFFERENCES BETWEEN DRAMAS:
-The ML in the Red Sleeve is way more toxic, and the FL is more often helpless despite her clever ways. It can be fun to watch toxic couples, it is like a guilty pleasure but this couple was unusually toxic, in my opinion.
-The King's Affection has a bit more humor. The FL is quite amusing as the 'cold ice prince' while the ML tries to assist her. His love is more pure.
-Overall, The Red Sleeve is more sad and tragic because the FL suffers a lot and she is way more helpless. The FL only wants to be able to make her own decisions. It's realistic, I guess... But it made me cry more and not laugh as much as in The King's Affection, despite this series having a few slow episodes in the beginning.

If you like one of these, chances are that you'll like the other one.

Same young female lead, she plays as twins in both dramas, except in the King's Affection, she plays a twin pair of a girl and a boy. Something happens to one of the twins in both dramas.
Again, Joseon Era setting, and political plots.
There is also a parallel of the main leads meeting at a young age, and starting to have feelings for each other since then.

Both dramas are sort of a gender flipped variation of each other with the same concepts: a FL who was supposed to have been killed at birth because she was born a twin but survives, twins who get mistaken for each other, one ends up murdered and the other stepping into their place, mistaken/unknown identities, assassination attempts and scheming within the palace, a childhood meeting between the main couple that the ML or both never forget even as an adult, and a happy ending outside of the palace.

- Cross dressing sageuk
- Female lead pretends to be a male in order to survive
- Forced to pretend since child due to decision by other people

Quiet and gentle, Min Jae Yi is everything a good daughter of a prominent family should be. Engaged to the son of the Second State Councillor, Jae Yi knows that the only way to bring herself and her family honor is to accept her fate, which she does with grace and charm. Devoting herself to learning everything she needs to know to become a good wife and mother, Jae Yi dutifully prepares for the future. Sadly, destiny has other plans for her future. Four days before her wedding, Jae Yi’s family is murdered. With no one else to blame for the unexpected tragedy, Jae Yi soon finds herself the object of baseless and horrifying accusations. Blamed for the death of her family, Jae Yi might not have had much of a future at all, if fate hadn’t decided to intervene. Bringing the lonely crown prince, Lee Hwan into her life at just the right moment, Jae Yi is saved from a dismal fate, but her salvation comes at a price. Plagued by a mysterious curse, Lee Hwan agrees to help Jae Yi, but only if she agrees to help him break his curse in return. Unable to refuse such an offer, Jae Yi agrees to the prince’s terms, setting them both on an unexpected path toward love. But what chance does their love have of surviving when one of them is a former murder suspect and the other is a cursed prince?

Both have a strong and smart female lead that disguises themselves as a man. There's also a scheme to overthrow the rulers and kill the crown princes in both of the dramas.

Lee Heon is the king of Joseon. 7 years ago, when he was a crown prince, his beloved wife died. To this day, he has not been able to get over her death. For the past 7 years, the royal family and government members have tried to get King Lee Heon remarried without success. The nation has also implemented a geumhonryung edict, which is a ban on all single women marrying during this time when the king has not married. People are furious over the marriage ban. One day, King Lee Heon hears of a woman named Ye So Rang, who claims the spirit of the king's late wife exists within the royal palace. Meanwhile, Ye So Rang is a swindler and claims to interpret marital harmony signs. She is arrested and jailed where Officer Lee Shin Won works. To get out of her predicament, she pretends to be possessed by a spirit in front of Lee Shin Won. During her ruse, she mentions that the spirit of King Lee Heon's late wife exists within the royal palace. She is then brought in front of the king and he asks her if she can really see his late wife's spirit. To survive, Ye So Rang acts like her body is possessed by the king's late wife. Ye So Rang's lies get bigger and more audacious.

Similar story, a woman pretends to be a man in order to be the king (even tho it was not a decision she made), then a young man starts working with her and they fall for each other

Fang Jia Hua is the successor of a business. His dream is to open a chocolate store and be an expert in chocolate. He ends up leaving his business and his family to fulfill his dream. Hong Xi En is someone who spent her days slogging and taking up part time work. One day, she ends up working for him and above all, she has to dress herself as a man for the job.