Lee Se Young plays a royal loved by a king in both dramas. Both Yeo Jin Goo and Lee Jun Ho are among the best actors playing Joseon kings.

> Both dramas by writer Kim Eun Sook. I'm recommending two shows she did, both of which are of soldiers, but the feeling of the two dramas are quite opposite. DOTS is romcom and Mr Sunshine is more melo.
> Both lead males are soldiers.
> The male lead in DOTS and the female lead in Mr Sunshine are both characters fiercely determined to protect their country
> The second lead couple' actors in DOTS appeared in Mr Sunshine as parents of the female lead.

Arthdal Part 1 is the first if the three parts released (all of which are Arthdal Season 1) while Arthdal Part 3 is the third part. There is also Arthdal Part 2, which must be watched between Arthdal Parts 1 and 3.

Arthdal Part 3 is the sequel of Arthdal 2. There is also Arthdal 1, the beginning part. But all these Arthdal Parts 1-3 are all part of Arthdal Chronicles Season 1.

Arthdal Part 1 is the prequel of Arthdal 2. There is also Arthdal 3, the third part. But all these Arthdal Parts 1-3 are all part of Arthdal Chronicles Season 1.

Both dramas are about the rise of Lee Bang Won. Difference is King of Tears is meant to be a more historical take while 6 Flying Dragons adds some interesting characters.

> Both dramas focus on court ladies
> The friendships of the different court ladies, their relationships with their higher ups, emphasis on how they should serve and belong to the king, is shown in both dramas
> TRIVIA: The female lead Lee Se Young is actually the child version of the rival female in Jewel in the Palace! Her characters in both dramas are both court ladies that are very talented. In Jewel in the Palace, she can cook since she was 3 years and is very knowledgeable in the kitchen compared to others. In Red Sleeve, she's good at writing and poetry.

Both dramas are about a princess who, due to circumstances, have to grow up outside the palace. For sometime in her life, she doesn’t know she’s a princess. She eventually returned to her kingdom and was a very good asset in helping/saving her people. Princess Deokman in Queen Seon Deok uses her wits, Princess Pyeonggang also does it plus she also fights some battles for her people.

> Both are well-made romance historical melodramas made 10 years apart
> Has a strong female lead that saves her male lead a couple of times
> Amazing performances from both leads to the supporting casts, and even a senior actor with a prominent role (Suyang in Princess Man and King Yeongjo in Red Sleeve)
> There are a lot of other historical romance melodramas (you can see from the other recommendations here), but these two dramas are both well made, received high ratings, and great reviews in Korea and abroad. Princess Man won best director and was nominated for other awards for Baeksang years ago, there’s a high chance the same will happen for Red Sleeve.
> Both female leads were called historical drama queens after their respective dramas aired
> The leads in both dramas received top excellence awards and best couple awards in their dramas' respective stations at the year end awards for their performances.

Both dramas are set during the reign of King Gojong. This means that the drama is set during a time when there is such a great transitional change going on in Korea (late 1800s). Korea, a kingdom known for being against the influence of foreigners (except maybe China or Japan) is shown to starting up to open to Western influences in both dramas, thus we see the lead characters use the gun more instead of the traditional swords (though some characters still use swords). We also see how Western influence is impacting the main characters. Example is how both female leads in both dramas got fascinated by the western objects they encounter in the show. We also see some men cutting their traditional long hair to fit to a shorter western hair, plus they also trade their hanboks to western suits. Big difference in setting is that Gunman in Joseon was showrn during Gojong's earlier reign while Mr Sunshine was during his later reign.
The character of Lee Joon Gi in Gunman also has similarities with both the leads in Mr Sunshine. LJG character and Lee Byung Hun's Mr Sunshine character are similar in that they suffered a lot in Joseon before they left for another country. Using an identity from another country (LJG using a fake Japanese identity and LBH becoming a US Soldier captain as US Citizen) and wearing Western clothes, their return to Joseon will lead them to more hardships to overcome before eventually becoming heroes to Joseon people. LJG character also has similarities to Kim Tae Ri character in Mr Sunshine. Both parents died, and both became masked vigilantes who do missions which eventually helped Joseon.
Basically, both dramas are about how people lived, survived, and even become heroes of Joseon in a time of impending change

> There are many crossdressing dramas, but what these two have in common is that the female lead lives as a man since a terrible event that occured in her childhood. She disguises as a man for so long that her identity has been as a man not only to others but maybe also to herself that she really got a man's mannerisms
> A love triangle existing between the girl pretending to be a man, her tutor/teacher, and another beautiful young woman (the difference is that the female lead in Painter of the Wind has feelings for BOTH her teacher and the beautiful woman).
>TRIVIA: Actor Bae Soo Bin is in both dramas and he's very important in both dramas. He's the King in Painter of the Wind who gives a mission to the two leads there while in King's Affection, he's the male lead's father whose allies are the main villains (not so sure if he'll stay a villain 'til the end).

=> Both are retellings of the love story of King Jeongjo and his beloved concubine Royal Noble Consort Uibin Sung (her real name is Deok Im but she's called Song Yeon in Yi San).
=> The court lady is shown to have a special talent (painter in Yisan, storyteller and writer in Red Sleeve).
In my opinion, Yi San should be the top recommendation for Red Sleeve fans, come on people, they're both MBC dramas about the story of one of Joseon's best kings and his beloved concubine.