Many many similar tropes; the family, the work, the coincidences, the rich man/poor woman, ...
Same writer, even similar characters names, common actors
The same cliches. You’re going to like the other if you like one

A widowed, rich, strict father of three
A lively young woman that enters the household
Both dramas are sweet and touching
The titles are ironically similar too
A worker (2nd FL) that has been by the ML's side for a long time.

Like episodes 3-5 in Adult Trainee, 9 End 2 Outs is a story of friends to lovers.
They are in different age groups, but the friendship is the same, and the romance is very lovely.

The love story of a bickering couple through many years
at the age of 29-30
With a similar sweet group of friends
Stress-free and meaningful dramas
about a deep meaningful relationship
A satisfying slow burn

The start of OBS immediately reminded me of the short web drama Flat. Two high schoolers that date and a documentary shows us their relationship as they grow into adulthood.

Life of a palace maid getting loved by the prince/king.
Teaches a lot about Joseon's palace life
Romantic Sageuk.
FUN FACT: King in Dong Yi (played by Ji Jin Hee) is the father of the King in Red Sleeve (played by Lee Duk Hwa) i.e. great grandfather of Yi San (played by Lee Jun Ho). All three loved a palace maid.
Red Sleeve is a melodrama, whereas Dong Yi is more... eventful and happier perhaps?

The story of the prince that grows as a commoner without knowing his identity is very very similar. He lives a very hard life. At some point, he gets kicked to the enemy’s country. He also falls for a woman from the enemy. Bonds with his real brother without knowing whom he is. In both dramas, the fate of many characters around him is the same. At the end, becomes the king (according to historical facts).

Summer Scent and Spring Waltz are both part of the four seasons series by the same director, but the stories are not related. They both feel warm, slow and romantic. And the stories follow four people hanging out close together.

One or both leads trying to recover from the wound caused by their past love
Their second chance at love is forbidden by their unfortunate circumstances
Leads from rich families
Great chemistry
ML chases FL first
Both dramas aired around the same time therefore having similar feel and quality

No wonder they have many similarities in the story
they have the same screenwriter
Both are very enjoyable
Bad Love is on the light side, while Phoenix is on the heavier side

Both plots contain finding the missing daughter, but they are different.
Family; parents, siblings relationships
Something that almost became a brother-sister relationship
Female lead going through hardships, and male lead helping her up
Heartwarming characters

Yeah the grandmas! Three grandmas!
No but really
There are many similarities
Feel good romance dramas, with mature characters leaning on each other and healing each other
Female lead who’s good at her job, leaves it.
Meets a guy from the county side who is skilled at many things.
At first both dramas don’t have a clear story direction.
I feel like MHOJD had more of an existing story line than HCCC.