Recommendations

Both have the same heartbreaking stories, and depicts the job as a host/stand-in service! Both FLs are experiencing marriage + identity problems. Both are depressing in their own ways.

Both are:
People copying with the loss of someone special for them,
Have situations regarding marriage and infidelity.
Depression.
Money and Job issues.

Both interesting, thought-provoking films about World War II. No Regrets for Our Youth focuses more on the pre-war period, while Children of Hiroshima focuses on aftermath.

These two movies are nothing but similar. But if you are looking for some eternal love with survival story and an unique plot line, you may try watching 'The Jade Pendant'. Though it might be underrated but it is actually a rare gem.
Hope you like it!

Both dramas are similar in most aspects. One of the main differences is that there is no divorced couple in Smile you. Watching OA gave me a similar feeling to SY. So if you liked OA, you will certainly like Smile You.

Both shows involve the leads struggling with trauma from their childhood. Eventually, they realize that they can begin the process of healing together. Heartwarming romance without second leads interfering with the relationship of the main OTP. The friends/side characters are also interesting.

Both films are directed by the same person - Li Xiao Feng, and are similarly pessimistic , with plot following a similar path

The main lead in WIL and Doctor Ian Chase from YAMS have some similarity in behaving like sociopaths but in Well Intended Love it is shown as romantic guy and in YMS as dangerous and prone to the worst. I think both of them are sociopaths and I strongly recommend to see and compare it ;).

Similar family story but Dear parents is lighter and funnier and has hope and happiness sometimes unlike The bond that combined the most Misérables family reality in a drama

The relationship between the leads is very understanding and mature. There’s some miscommunication as well, but not of the type that makes it unrealistic. Their situations make it plausible for them to react that way.

-Mystery solving duo with an opposite personalities
-Have the same "cozy" vibe (Grading, Score, and Cinematography)
-Episodic and fast-paced drama

Both dramas have a very similar plot. The only difference here is the target of the main character’s next target.

They both have a thriller feeling and a very dark back story
His daughter was asking for help in a discreet manner yet he was clouded with the insane “salvation”.
Sang mi’s father grief that turns into an obsession cause he thought he couldn’t save his son in this world he could at least save at the other world he thought of that as a second chance to correct his mistakes to hold his world that was falling apart and his son’s death was the last straw he felt that he was the reason for his son's death and his remorse was the thing that led to his end.

= Same lead actors as the main couple (I personally don’t find their chemistry the best in both dramas but the female lead is more bearable in Time Between Dog and Wolf than Gunman, perhaps because there’s a second more compelling female lead in Gunman).
= The actor who plays the real dad of the female lead in Time Between Dog and Wolf is the same actor who plays the dad of the male lead in Gunman in Joseon
= Father of a woman (female lead in Time Between Dog and Wolf, second lead in Gunman) who has a thing for the male lead is the one who killed one of his parents
= Male lead has two identities in both dramas, one before his supposed disappearances (death) and one after. His second identity is used to spy on the villain for the sake of revenge plus other things he or the organization he belongs to need to accomplish.

Similarities:
-Princes falling in love with a maid
-Rebellion
-inter competition between all the princes
-lover triangle
-The characters Wang Wook (Moon Lovers) and Yan Xun (Princess Agents) have a very similar goal, but end up hurting the one they love

Princess Agent has defiantly more danger and action pact.
-secret organizations

Moon Lovers: Scarlet Heart Ryeo focuses more on the romance and relationships between the Female main lead and the Princes.