Both dramas deal about corruption in the law-enforcement. Both have a detective-lawyer team and both male leads have a similar background story. And both of the male-leads-partners had something to do with the investigation of the cases of the male-leads. Generally it gives a similarish.-vibe.

Both dramas have a similar investigation duo, both female leads have a close connection to dead people and can interact with them. Both female leads have a family that has many secrets. And both dramas deal with crimes and children that are somehow involved in those.

Both dramas are long-episode long dramas about families. Especially "mothers" play an important role, and so does the difference between social classes. In both dramas we have a female lead with a similar background and both yearn for their real family/family member.

Both female leads know more about the male leads than the male leads are aware.
It has so many similarities, apart from the fact that in My Mister we have someone quite broken whereas in Big Issue our female lead managed to rise form that and became someone quite strong.

1: fBoth drama are written by the same screenwriter '
Apart from the fact that one is build around politicians and their secrets, and the other about paparazzis and the things they discover, both dramas are extremely similar. From the character similarity of our male leads are nearly identical, both have a trauma from their past and both are at the bottom. Both meet women with a near identical character, and both women play an equal important part. although in Big Issue it is slightly more.
Definitely give the other a try if you like one of them.

Both dramas are dealing with crime cases and in both dramas we have an investigation duo where on of them has got a heart transplant that is connected to the people and the story.

Both have very similar male leads, both are working in the lawyer/attorney are and discovering the truth behind cases, that are bigger than it seems at first.. Both dramas have a lawyer-detective partnership that tries to figure out what is truly going on.

There is truly not much that is separating both of them for now. "Stranger" is truly a master piece of investigation/crime/mystery dramas," Confession" seems like it will follow it in this category.

Right from the first episode onwards "Confession" gives off a "Signal"-like vibe.
We have 2 very similar male leads, with a nearly exact personality and background, a team that is as similar as can be, characters and even storylines that are very similar to each other.
If you have enjoyed one, there is a high chance you will enjoy the other.

Both dramas deal about 2 women that are divorced and go through a hard time. After a long jumping between jobs, both women end up, with the help, from in Romance is a Bonus Book, a friend, and in Cunning Single Lady, ex-husband, at a company as intern. Both have that man as their superior and keep it a secret from their coworkers.
Both stories give off such a similar vibe. Both women reminded me a lot of the other while watching the dramas.

Just one thing: please ignore the horrible synopsis of "Cunning single lady", it gives such a very bad impression, and trust me, it is completely wrong. There is by far more to the drama than what one thinks at first.

Both deal about friends who realize they feel more than friendship for the other person. Both deal about the nearly same story, so if you like one of them you are bound to like the other as well

Both dramas deal with mothers who's daughter was murdered and look for the truth of what happened.
Both mothers are strong women.

Both deal about a small group of people that receive orders from a *leader* to investigate cases. Both give off a similar vibe. Both deal with characters that have a tragic past and try to get revenge.