There's not much in common between these two shows but I will say there is one key detail that makes them similar...

In Secret Garden,
the second lead, Choi Woo Young (also known as 'OSKA'), has a difficult relationship with the second female lead, Yoon Seul, after she overhears him dismissively telling a mutual friend—who happens to be interested in her—that she was just a fling and meant nothing significant. This deeply upset her, prompting her to break up with him and take a long trip to work on herself. Upon her return, she sought revenge by making herself an unavoidable presence in his life, serving as a constant reminder that he wasn’t the only one affected by their breakup. Her actions eventually drove him to make reckless decisions.

In When the Phone Rings,
the leads Baek Sa Eon and Hong Hui Ju are two married strangers, who happen to be put in a hostage situation over the phone. Baek Sa Eon response leaves Hong Hui Ju devastated and disappointed. Right then and there she decides to seek an opportunity for revenge. She impersonates her kidnapper by calling him through the phone the kidnapper used. She seeks an opportunity to make him miserable for not caring enough for her on the day of the kidnapping. While seeking freedom from her marriage she is given the chance to speak out her bottled-up feelings.

These stories are not the case of a usual misunderstanding in dramas but a case of miscommunication of feelings.

Basic Similarity:
In both shows the leads connect for their love of a certain beverage.
-Both have workplace romances.
-Both FLs are very hard working people who have to take care of their family. (They could both be considered bread winners if the the FL's brother in brewing love lives separately).
-Both ML's come from wealthy families.
Differences:
ML's personalities are quite the opposite and their intentions in their business is completely different. In Coffee Prince Han Gyeol opens up a coffee shop to impress and prove his grandmother wrong. In Brewing Love Min Ju is a CEO of a brewery company who comes from a wealthy background but seems to be self-made because of his broken relationship with his father.
-Their personalities are completely different. Min Ju is sensitive man who self isolates himself and only focuses on company. Han Gyeol on the other hand is typical rich playboy who never worked a day in his whole life. He's different from the severally introverted Min Ju.

One word CHILDHOOD LOVE!!

Similarities:
-One of the main leads goes to The United States for a while.
- Both ML are in their 30s and have successful careers.
- Both FL are in a "slump" and are struggling to succeed.
- After not seeing each other for a long time, they return fully, always budding heads.
- Both ML had a tough childhood with bullies but the FL came to the rescue.
- Both FL overreact to almost everything.

Differences:
-In Oh Youngsim the ML had already confessed his feelings towards the FL while they were young.
- In Oh Youngsim they are both heavily involved in one another work.
-The main lead reason for coming to Korea is different.
- Both have family relationships, but Love Next Door takes it up a notch.

First of all, Both give a similar vibe with how the character were written to be. Both shows plots are a ridiculously scenarios. Both shows main leads have to figure out how to coexist and eventually they find that they enjoy spending time together. I don't know if it's just me but I think since they both are from the same network company maybe writers or producers from one show worked on the other show, making them very alike.

Other Similarities:
Both Female Leads are strong, hardworking, quick witted women.
Both Male Leads are misunderstood in the beginning and overtime learn to be understood.
-It's still too early to say that the ML from wedding impossible is misunderstood but I think he acts out but he's intentions are different from what the FL sees.

Both Shows Plots are somewhat different but both FL have similar experiences. They both are surrounded by males who find her the FL interesting but not necessarily romantically. They have both feel in love for narcissistic, chaebol(Heir) and have live with th e difficulties of their families and their lifestyle.

More Similarites:
BOF has a somewhat tomboyish FL
They are the go-getter type
Both have experience with delivery services. ;)

Both Show are great in their own style but differently worth watching these classics.

Both originated from a Webtoon that has a Gumiho present. One that very obvious and another who isn't. In both drama the main lead(s) are/is trying to figure out a solution to accident they have created. (Spoiler Alert) Around the second half of the drama the female leads gets her memories erased and we see the ML struggle to get the girl to fall in love again. Do they succeeded? That's something you have to find out by watching both shows.

First of all, both Male leads are wealthy heirs to a big company. Second of all both female leads work very closely with the male leads. Both dramas have male leads who are narcissistic chaebols who suffer from the trauma of trusting people and both female leads are strong hard working trusting leads.

Other Similarities:
Both fit the poor woman, rich man trope.
Both Male leads start off badly with the female lead but end up falling first and harder.
Both aren't strict with just office/business settings.

Strong Woman Do Bong Soon is one of those "you must have watched" dramas that most people get into first. (Basically, a beginner drama most people have watched). It's also very unique from traditional office romances because of the crime and supernatural elements. It's one of those comfort dramas that leaves you with such incredible satisfaction.