Recommendations

Both have gentle romances with the prince/royalty. Female has some more worldly knowledge than him and teaches him outside of his comfort zone.

Both have similarities because The second Male lead is the female lead's brother except with In Youth the main Female Lead brother is an enemy to the first male lead, same situation with the Negotiator except the second male lead sister works at both businesses, under disguise, negotiator is more about making negotations and In youth is mostly about friendship and romance, both have business corporations, both have business and romance, except In Youth is mainly about friendship and solving problems and Negotiator is mostly about Romance.

These shows are similar in the fact that the male lead forgets things daily, due to something tragic happening in his past. In DJ the CEO male lead forgets everything at the end of every day but after meeting the female lead he doesn't seem to forget about her due to his feelings for her.
MGIAA is about an alien who has landed on earth, she had something taken away from her, preventing her from leaving earth. The man who stole her item is a man with a secret, due to something happening as a child, he forgets every woman he has ever met when it rains, the only person he seems to remember is our female lead.

If you liked either of them I suggest you watch the other :)

both have minor school girl one marry to older man other marry minor man as her this marriage force by their parents both couple find it awkward so keep it secret in both couple one of the partner is positive toward this marriage and for other its burden

While these are set in different stages of life, both are very light and fluffy webdramas with love triangles. They both have smart female leads and sweet, but grumpy male leads.

Both are love stories set in school (high school for best mistake and college for queen of the ring). Both of the romances kick off with a misunderstanding/straight up lie from the FL, and a love triangle ensues.

High school drama, love triangles (in as in click your heart, a weird love pentagon) and have a lighthearted, fluffy feel.

Both dramas center around young love, first love and friendships. They have similar vibes despite one being set in high school and one in college.

Both are high school teen stories with love triangles and high school drama. They have similar vibes and are really shows rat and fluffy.

Fated to love you is the remake of Taiwanese drama you're my destiny..although I prefer Korean remake but if you want to watch the original series then you can go for this one.female leads of both the dramas are cute,kind,naive but the male lead of Korean remake is better than the original series male lead

both dramas are kinda the exact opposite but the same? in FCJMA we have a commoner about to get married only to be taken away and announced as the king, while in 1DMP we had a king/prince who forgot he was a king/prince and ended up "getting married" to a commoner ;)

Both are about a young child who have an incurable disease that exist in the real world. Oh My Geum Bi is about an 8 year old who was diagnosed with Niemann-Pick Disease Type C which has been nicknamed childhood Alzheimer disease. Geum Bi is that 8 year old child and does her best to exercise her mind to keep the inevitable from happening... she is told because of her disease she will eventually wont be able to remember anything and will no longer be able to walk or take care of herself at all just like with an actual Alzheimer patient. To make matters worse, because of the disease her auntie that had been raising her couldn't handle raising such a sick kid and decides to abandon her one day and only gave her information about her biological dad and to go find him to have him raise her. But that biological dad is a criminal scammer who ends up arrested... can this man clean up his life and take the responsibility of properly raising his child? What will he do when he finds out about her disease? That's where this story begins.
It sounds fairly similar to the theme of this drama and so if you like one, you will probably enjoy the other. I personally loved Oh My Geum Bi because of many things but mostly I was glad to know that this disease exists!

Both movies have a strong female lead who is good at beating/killing people and has a mysterious past.

Both women have a hobby of peeping as a sexual fetish and both drama series are adapted from manga series.

Both detective series.
Both male leads are good at their job
The female rookie helping the male lead (also the same actress playing her)