Both dramas give very similar vibes and the relationship between the couple is very similar.

Both dramas follow a cold musician and a girl who has a huge passion for music but is unsure on how she wants to pursue her dream due to having no skill in playing instruments or singing. The MLs in both dramas are from rich families who are not supportive of their dream, the MLs want to prove their father wrong and use their talent to become truly famous. But due to the toxic music industry they are led astray and are not happy with their career, leading them to become cold, selfish and lose their passion. The FL helps the ML go against his superiors so that he can create the music he desires and go back to being passionate about music. The couples start off on the wrong foot and are always squabbling with each other but due to FL being more caring towards him then others (Others just use him for his talent for money), the ML falls first. Not only does the MLs life change but as both the dramas continue, the FLs start to realise their dreams and make their dreams come true with the MLs help.

The only difference is that MIFOL features a contract marriage between the leads. This does not happen in TBSITS but there is cohabitation in both dramas.

Both dramas feature a FL and ML that have an arranged marriage, before meeting face to face they both refuse to get married, ending up with one of the leads marrying another (In TLOJY the ML marries her sister and in PS the FL marries a general).
But the two fated leads later meet and begin to fall in love without knowing the others true identity, in these parts of the dramas the FLs conceal their identities (In TLOJY the ML also hides his identity though).
Once the couple realizes their lovers true identities and their true feelings for each other they go through a lot of struggles so that they can marry each other, after a lot of failures they finally have their happy ending :)

Both plots are 'gender benders'. (TROTAR is slightly) and have a lot of comedy.
In TROTAR a girl goes into a world that she wrote, Hua Yuan City is a city where instead of men being in power, women have overall power. Men are not allowed to be officials, they can't own businesses and they can't even join the army. A powerful man from the city near them (Where the rules are different) marries of FL (who realizes she is the evil princess of Hua Yuan City).

In OMG the FL is a powerful General that is looked up to, she acts quite manly whereas the ML is a handsome yet useless, cowardly man who acts femininely.

I get similar vibes from these dramas but the plots are in no way similar.

Romance between a Doctor and someone working in the military. Dear Uniform hasnn't started yet but these stories seem to be very similar in terms on the relationship between the leads.

Both about a man who has Hyperthymesia (Remembers pretty much every moment in their life in great detail), due to this they remember something that really hurt them in the past. But their condition eventually leads them to finding the female lead and falling in love despite both leads having struggles due to the past.

Both male leads are well known (FMIYM= News Anchor. MLEM= Visual Artist/Photographer). Both female leads have a bit of popularity but are trying to make a name for themselves (FMIYM= Actress. MLEM= Ex Idol, trying to get fame in fashion industry)

MLEM I would say is more of a Rom-Com with only a few serious themes.

Junichi is a man who is unknown, he travels around and wherever he goes he happens to meet a girl and makes her happy intimately and makes her realise what is wrong with her life in some way and shows her, without words, how to be happier.
In RDWCS the story concentrates on the lives of five people who work together. As the story goes on they all discover what they are doing wrong in their lives and some even find unexpected love.

!!mature content!!

I would say Junichi is more of a Psychological drama, whereas RDWCS is a Comedy.

They are both similar in terms of time travel but they don't really have a similar plot.
In DBTTQD, the leads met in modern times due to a magical object (She had a lantern and it allowed the prince from the past to come into her home when he slept, they fell in love during this time) , but they were then separated, causing the female lead to go into the past and find him.

UL is about a girl who enters a game to find her true love, the area she goes into is historical and she meets a lot of nice men but the one she falls on love this is the man she hates.

UL is more of a comedy whereas DBTTQD is more political. But both dramas contain, Fantasy, Action, Wuxia and Romance(More Romance in UL) :)

Both similar in terms of time travel.

In DBTTQD, the female lead goes into the past to find the prince she fell in love with in modern times (due to an ancient object they were able to meet but they were later separated).
In LBTI, the female lead enters a game (That is historical themed) and falls in love with someone unexpected. (This is a Wuxia drama)

DBTTQD is more of a Political drama whereas LBTI is Wuxia. But both stories contain Fantasy and romance. :)

Very similar dramas
TEL is about a girl who goes back into the past and she finds herself sharing a body with another woman (Fl is more outgoing whereas the other is serious and silent) who tried to commit suicide due to being forced into a marriage with the 8th prince, stopping her from being with her lover. Our female lead falls for the 8th prince, causing the 8th prince to be confused by the true personality of his lover, what is her true personality?

In DBTTQD, the female lead goes into the past to find the prince she fell in love with in modern times (due to an ancient object they were able to meet but they were later separated). The leads go through struggles when the fl goes into that past as they both forget each other upon the fl's arrival, the fl needs to try and fit in as she tries to remember the reason for her travel into the past and remember her true lover.

Both dramas show the male leads fighting for the throne and power whilst trying to protect the female lead.

LMIYD isn't medical but I think they are similar in the fact that the male leads are very talented in what they do. In Doctor John the male lead is a talented doctor who was wronged in the past. In LMIYD the male lead is a skilled criminal phycologist, he is well known and one of the best in his field. Similarly to in Doctor John, people find him suspicious at first and think he's a bad person, but with the help of the female lead (that they slowly fall in love with), they are accepted and people realise their skill in their field. The female leads also become able to accept their tragic pasts, whilst falling deeply in love with the troubled male lead.

I highly recommend both dramas. They are both very similar, just one is based on medical situations and the other, criminal situations :)

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 :)

These dramas are nothing alike but for the people who wanted to see more of The Grim Reaper and Sunny's relationship or Kwon Jung Rok and Oh Yoon Seo's relationship you should watch these two dramas. Their romance in both dramas is very different but sweet to watch. Lee Dong Wook and Yoo In Na have great chemistry :)