They both have a similar tone when it comes to the relationships in these movies.
They are both about love that not a lot of people in society accepts: A Muse is about a relationship between a teenager (still in high school) and a much older man. Then Boku wa Imouto ni Koi wo Suru is about a brother and sister in love with each other.

They are both amazing stories about the lead not giving in to their illness.
1 Litre is a true story while A Millionaire's First love is not.
They are both uplifting, tear jerking and great movies to watch.
The only difference is that A Millionaire's first love has romance, while 1 Litre only hints at romance (but not the main theme).

They are both take place in reality game where the contestants are trying to win money.
They both have similar tone and mood of the movie.
100 Million is a bit more darker than Liar Game because LG has more humor than 100 Million.

They both star Lee Min Ki in a darker roles.
They both are great suspense/thriller movies.
The difference is that A Million is a game show and Monster is a revenge story.

They both have obsessive, forbidden love story.
They both have a similar tone, but Frozen Flower is more intense when it comes to the love line.
Both love stories are dark and not for the faint of heart.

They are both are based on true stories that happened during the movies' timeline. They both are very good and recommended to anyone who love war movies. Bring tissues for both of these movies!!!

The only difference is that 71 takes place in the Korean War and My Way takes place in World War II.

They are both about multiple men learning how to take care of a baby on their own. 8Uppers is a little bit more serious than Waikiki, but they are both funny.

In both, the cast a lot of international cast in one drama/movie. Both have military as a main plot point.

The tones are not similar, but both are good in their own right. DOTS has romance, and is light-hearted fun, bit with some serious moments. My Way is more darker and has a more realistic tone of war. No romance at all in the movie.

They have similar tones. They are about high school students forced to face reality when something catastrophic happens to their ordinary life and fight to survive.
In Death bell, a high school student s are being killed one by one for n unknown reason. In LIMIT, a whole class goes on a field trip and then ends up
in a accident and the the last survivals fight to survive to get home.
They both have suspenseful tone and both a worth the watch.

Both have Lee Min Ho as the male lead and both have action in it.
They both have a similar tone to it, but Gangnam 1970 doesn't have a lot of comedy and doesn't have a lot of romance.

They are both reverse harems and have similar tones. Have similar cliches: love triangle(or square), hard working female lead with spunk, multiple male leads, etc.

Both female leads are in high school who work hard to be where they are today. But the reasons are different. But both are in debt.

They both are reverse harems(one girl with multiple if guys in her life). The tones are very similar. But CAT4K is a cohabitation drama whereas 7FK is an office/endorsement drama.