Recommendations

Fun romantic family dramas, although in one the family is against the main couple and in the other the family want them to be together but they hate each other, they have the same feeling and are really enjoyable.

Both movies are in historical settings and are about young men whose androgynous beauty sets off highly chaotic situations.

Both very touching slice of life dramas about a terminal illness. Also very nice display how the families react.

Both are noona romances. Where older women date younger men and realize they can find love in unexpected places. There are also 2 male leads who seem suitable for our heroine.
There are also other stories surrounding the main couple. The storylines of a few of the secondary characters are also similar.

Both deal with older women dating younger men ad the conflicts they face. Both younger men seem directionless at first but both have issues as to why they live the way they live.

Both are about nine tailed foxes (gumihos) that tries to find a thousandth person to become a human

They are both about a young boy who is wronged by the law. In both cases the boys have super-abilities (one is more ..fantastical than the other). Both stories also contain an older noona through whom the boy's goal of bringing the criminal to court is accomplished. This noona also serves as the love interest.

There are even parallel scenes.

In other words, they are pretty much the same, except for casting, music, and circumstantial differences. Soo Ha and Dae Gu would find they have waayyy tooo much in common, if they met.

Oh, but there is one notable difference: Hye Sun is bold and sassy throughout the show, Soo Soon only manages to be bold and sassy while she's still a teenager. That side of Soo Soon dies out once she becomes an adult.

Similar era (gangster and politician join hand in hand, the importance of constructor), very similar background music (was it even the same?), similar style of presentation, lastly they tackle similar theme (injustice, rich people do bad things because they're bad while poor people do bad things because they have to) in a similar way

Both dramas have a similar feeling with dark, depressive tone, the characters are also very similar and in both dramas OST is really great. Mature dramas with very good actors and difficult storyline. I have enjoyed in both of them because I liked it that these are very different from all others typical Korean dramas with characters who are full of faults and where the chemistry between all actors is just amazing. A little note- What happened in Bali is much darker, tragic and more psychological that Que sera sera but definitely both of them are worth watching.

In both the leads pretend to be a couple. Although in PM&I, they pretend to be married while in MND they pretend they're engaged.

It has most of the same comedy vibe. In one they're pretending to be a couple, in the other one, one of them pretends he is gay.

Both series are about the fragile and unbreakable relationships between friends, and how school, each other, and other outside factors affected those relationships.

Both series are about students in high school trying to live their lives, discover who they are, and reach junior year in peace. Though Reply 1997 heavily revolves around romance, it still has the message that you are nothing without your friends.

Both are about revenge dramas with very good story to tell each. Our heroes have tragic pasts which haunts and drives them.

Very similar. Teenage vampire love. Young vampire's coming of age, love with a human, some unfrendlies that get in the way...