Recommendations

The FLs in both dramas are older than the MLs.
The women value their careers and work hard to achieve their goals. The male characters both have a role to play in the professional success of the FLs.
The MLs start out in the professional world and want to succeed in their dream as a Designer in The Rational Life and as a musician in My Fated Boy.

Both deal with the same subject, which is state-sponsored human experimentation in World War II, and how these doctors--supposedly guardians of human life--ended up doing the very thing that is antithetical to their profession.

They have same vibes in working and pushing to become better in their career. female lead are the same in hard working , naive kind of personality.

Slice-of-life romance of mature adults with a bit of drama and enough comedy.
- ML is somewhat lost in life in the beginning, thinking of changing or actually changing careers.
- ML are rather reserved but nice.
- FL approaches first and warms his heart. She herself doesn't need saving, she has an established life of her own.
- There's a lot of trust and mutual support in both relationships.
- Well written smart dialogs full of meaning.
- No love triangles or evil characters (there is a secondary couple in Run On).

The greatest difference is the amount of chemistry (YAMG couple is HOT, RunOn couple is very tame).

It is set in high school and has the first love feelings. In both the series, the leads met during their childhood and rediscovered friendship and love when fhey meet again during high school.

FL is an aspiring series script screenwriter While napping, she is transported into her own story, becoming the Third Princess Chen Qian Qian, a side character, killed off in the third episode by the male lead, Prince Han Shuo. Armed with the knowledge of her own script, Xiao Qian is determined to stay alive and find her way back home.

Both are romantic dramas with amazing high profile actors. The dramas focus on the love story of 2 completely different people and how they come to care for each other. They are also based on the novels by acclaimed chinese authors

Similar feel, both take place before and during WW2, both are about family connections and the lives of citizens during war. One is a movie and one is a drama. Boku ga Warau to is brighter

They are both dramas centred around family and the struggles they face. The characters are very realistic and the plot is very grounded. It's easy to relate to these stories.

The overall vibe and setting is similar. The way the story unwinds and how grounded and realistic the characters are is also very similar.

WARNING SPOIL : ML in it's okay that's love and FL in Crush both have psychological problems of the same sort

Both have females working in an office setting, making their way to success, both have an older woman/younger man relationship

Same director - same aesthetic but in color. Both are wuxia, both share intrigues and heart-break about the hazard of events that is life.
The stories are both epic.

Have the same girl group survival concept of placing girls in a temporary group and elimination. Some of the Chinese members in Girls Planet 999 also participated in this survival show such as Su Ruiqi, Shen Xiaoting and Ma Yu Ling.

Mhm this is difficult - I watched both dorama over 8 years ago.
Both however are slice of life, of the FL getting back into craft and trade jobs. They both might over-romanticize getting back into traditional Japanese jobs, but I liked and found alike the calmness of watching them learning their respective crafts and finding themselves while doing so.