Painting plays an important part in both dramas. It’s so important since the female lead in both dramas have talents in painting. King Jeongjo features in both dramas (though he’s not the main character in Painter). Since it’s both about King Jeongjo, you expect to see a glimpse of his sadness and grief due to the early death of his father Prince Sado, political battles against his step-grandmother the wife of the former king, plus you can see a loyal minister to him named Hong Guk Young.

For Binjin fans. Hyun Bin and Son Ye Jin both appear in both shows. There is no loveline in The Negotiation but there is in Crash Landing on You. If you can't get enough of the two together, I recommend one show for fans of the other and vice versa.

They are not very similar, but both of them are Song Joong Ki's dramas. I am recommending Arthdal to SJK fans watching Vincenzo because it is a very underrated drama and I feel that SJK great performance in Arthdal needs more atttention. Aside from Song Joong Ki, Yang Kyung Won and Choi Young Joon (also in Vincenzo) also had small/supporting roles in Arthdal.
Arthdal comes in multiple seasons. As of March 16, 2021, only the first season is released. The first season is divided in parts, of which this particular show of Arthdal I am recommending is part 3.

They are not very similar, but both of them are Song Joong Ki's dramas. I am recommending Arthdal to SJK fans watching Vincenzo because it is a very underrated drama and I feel that SJK great performance in Arthdal needs more atttention. Aside from Song Joong Ki, Yang Kyung Won and Choi Young Joon (also in Vincenzo) also had small/supporting roles in Arthdal.
Arthdal comes in multiple seasons. As of March 16, 2021, only the first season is released. The first season is divided in parts, of which this particular show of Arthdal I am recommending is part 2.

They are not very similar, but both of them are Song Joong Ki's dramas. I am recommending Arthdal to SJK fans watching Vincenzo because it is a very underrated drama and I feel that SJK great performance in Arthdal needs more atttention. Aside from Song Joong Ki, Yang Kyung Won and Choi Young Joon (also in Vincenzo) also had small/supporting roles in Arthdal.
Arthdal comes in multiple seasons. As of March 16, 2021, only the first season is released. The first season is divided in parts, of which this particular show of Arthdal I am recommending is part 1.

Everyone knows Song Joong Ki from DOTS. On the other hand, this extremely underrated drama that he did in 2019 called Arthdal Chronicles deserves way more love and attention, thus I am recommending Arthdal to SJK fans who became fans from DOTS. Arthdal Chronicles comes in multiple seasons. As of March 16, 2021, only the first season is released. This is part 3 of the first season.

Everyone knows Song Joong Ki from DOTS. On the other hand, this extremely underrated drama that he did in 2019 called Arthdal Chronicles deserves way more love and attention, thus I am recommending Arthdal to SJK fans who became fans from DOTS. Arthdal Chronicles comes in multiple seasons. As of March 16, 2021, only the first season is released. This is part 2 of the first season.

Everyone knows Song Joong Ki from DOTS. On the other hand, this extremely underrated drama that he did in 2019 called Arthdal Chronicles deserves way more love and attention, thus I am recommending Arthdal to SJK fans who became fans from DOTS. Arthdal Chronicles comes in multiple seasons. As of March 16, 2021, only the first season is released. This is part 1 of the first season.

The dramas are not very similar but they are the only dramas (as of 2021) that is set in historical times where Han Hyo Joo is the female lead. While her character in Iljimae is a rich noblewoman compared to her lowborn character in Dongyi though, both her characters are depicted as nice, kind, and good-hearted. Another similarity of both dramas is that Kim Yoo Jung plays the child actress of Han Hyo Joo in both dramas.
(Including Kim Yoo Jung's characters in Moon Embracing the Sun and Grudge the Revolt of Gumiho and Han Hyo Joo's Shining Inheritance character, I somehow feel like those two actresses are the go-to of casting directors back then (2008-2012) when they needed someone to play the kind, noble, and good-hearted beautiful female lead (basically a Cinderella like character).

Yi San is about Dong Yi's great-grandson. The old king in Yi San is the same character as Dong Yi's young son. The main romance plot is also quite similar. Both kings in the drama have a queen who can't give him a child. The king's main love interest is a humble ordinary young woman with a special talent in arts (Dong Yi plays haegeum while Song Yeon from Yi San loves to paint). (Something funny for me is that the actresses for the female leads, Han Hyo Joo and Han Ji Min, looks similar). The main female love interest also has a warrior brother like who has a one sided love for her. You could also notice the similar directing style of both dramas, both were directed by director Lee Byung Hoon (not the same person as actor Lee Byung Hun) who also directed Jewel in the Palace. They also have the same writers (Jewel in the Palace writer is different though, writer for Jewel in the Palace is the one who wrote Queen Seon Deok).

=> Strong female lead characters that started in very low positions (though the female lead in QSD is actually a real princess that didn't know her identity)
=> Female lead pretends to be a man at the earlier part of the series
=> Two equal love interests (Bidam vs Yushin, Tahwan vs Wang Yoo), even today, fans of both series argue which of the two love interests does the female lead love more
=> A third male character (Alcheon, Taltal) is technically not a love interests but is very supportive of the female lead
=> Actors Jung Woong In and Kim Jung Hyun (different actor from the one in Mr Queen and CLOY) are in both dramas and both their characters are on the evil side in both dramas
=> Female lead often has to fight with other women of high positions in the court before she reached the top position.

1. Lee Joon Gi is male lead in both these historical dramas. We know he did a lot of historical dramas, but we can argue that these two are most successful. Iljimae gave him Top Excellence in SBS Awards as well as nominations for Baeksang while Moon Lovers gave him international popularity.
2. Lee Joon Gi is rivals with a half brother for the love of the same woman. Except in Iljimae, he and the half brother do not know they are siblings. Also, there is less focus on romance in Iljimae.
3. Lee Joon Gi wears black mask in significant parts of both dramas (though the reasons for wearing masks in both dramas are different)
4. Actor Jo Min Gi plays Lee Joon Gi's dad in both dramas.

*Interesting trivia: Kim Yoo Jung, the female lead in Moon Lovers' rival show Love in the Moonlight/Moonlight Drawn by the Clouds, actually plays the child version of the female lead in Iljimae.