Both are medical dramas with a healthy slice of disasters. D-Day is more medical with higher disaster, and a sweet romance, while DOTS has heavier, sweeter romance.

Rich weird guy falls for poor, clueless girl. Rich Guy falls first and pursues her even though he keeps denying it. His behaviour is totally crazy that everyone who knew him wants to know if he went mad. He faces up to his feelings soon though, and takes care of his girl.

Both are boss-employee romance.

Overall, High-End Crush was sweeter, and more hilarious, with the male lead so confused and behaving abnormally.

Triangle is about brothers finding each other after years and the most powerful one is a gangster. K2H is about a prince learning to steer through danger and politics. Two very different dramas. In Triangle, the lead turns from a pitiful, poor, and powerless gangster to the most calculating, powerful one. He steers his people through danger and comes out on top. By the middle, there is no one who doesn't feel apprehension when they hear his name. In King2Hearts, the degenerate playboy prince transforms into a smart, respectable, highly admired leader. Also, in both, the leads were called 'trash' in the beginning.

JaeJoong stars in both. Triangle was about him (not so) covertly taking over a city and a business. Spy - he worked for his country. Triangle was better IMO

IPA is also a Spy drama. Parents have a prominent role in the drama too. IPA is comedy though.

Same kind of story - new secret agent guy, girl who is caught between him and the agency. Level 7 had gaping plot holes though, and Parachute was done much better.

King2Hearts was 100% better. If you want the training, the growth of a playboy into someone formidable, who never looses the romance and fun in life, K2H is for you. The female in K2H is also 100% better than the character in 7th Grade. To me, 7th grade tried to pull a K2H and failed badly.

Romance! Historical! Romantic Triangle, though 1 guy wins by a landslide. And production quality is great.

Both historical, both about an enduring love. Princess' Man does have less cheesy scenes, but you feel the love between the leads a little more. Also, both are about political power and based on true events and people. Nice ending too.

Il Mare has issues of time discrepancy too. The romance was nice as well.

Past relationship teacher and student. Sad though, with enduring love.

Hello Schoolgirl was a little deeper. And it's not student - teacher, but the age gap is there. The schoolgirl and the older guy fall in love. It's fluffy cuteness (Kinkyori Renai was fluffier and cuter) and the ending was nice.