Child Lead with elements including child abuse. Both films are sad and realistic with the setting as well as the melancholic tone.

High schoolers fighting to the death under different circumstances. The cast in each are both mainly high schoolers that are frustrating to watch.

Both use makeup to promote self confidence rather than vanity.

Makeup transformation, although they were both beautiful either way.

Both based off webtoon/manga

School romance

Duel male leads. One is for justice while the other uses more unorthodox ways to find the killer of a family member.

Death of a family member, lots of flashbacks.

Bromance.

Rain scenes.

Both take place mainly in apartment complex
Both have strong female leads
Both have an infection that is spreading for unknown reasons with little about it being told to them
Both have blood, strong special effects
People infected kill people whether that's zombies or monsters

I know this might sound weird, but the main serial killer in each one is hot...
Both trying to stop a serial killer, both live in apartment complex with the serial killer, both have blood/knives

Both couples keep their relationship a secret
Age Gap Relationship between Younger Male Lead/ Older Female Lead
Multiple couples, slice of life in each
Not too dark, easy fluffy romance
One night stand turns into romance with the main couple
Female lead is the boss to the younger male, he's below her in the workplace

Both of these are very subtle and not in your face when it comes to homoeroticism. Showing characters gradually develop feelings, as well as having a girl in the mix to complicate things. The endings are both bittersweet and there are internal doubts in characters in both of these dramas.