Both feature a self-aware manga character as the FL who is determined to change their story. In both their world will disappear when the manga ends.

A character created by the FL comes to life and enters the real world. He then falls in love with the FL.

In HL, a character from a manga enters the real world, WF is a person from the real world entering the world of a manga. They then fall in love with a person from that world while attempting to change the story.

Both feature a FL's character of her story coming to the real world and the two falling in love. DD is a novel, TMRFTS is a manga.

The dramas are sort of the reverse of each other - WF is a real world person entering a manga world, TMRFTS is a manga character entering the real world.

Both are short Chinese dramas about a manga character coming to the real world to convince the writer to change or continue their story.

Both feature a self-aware manga character who tries to change the plot of the story to give themselves a happy ending (EY from within the story, TMRFTS by coming to the real world).

Manga character comes to the real world, falls in love with FL who is a manga artist/artist's daughter. The manga characters "fade" as the artist draws/changes things, and there is a villain in the real world who is also from the manga world.

Both dramas feature time travel bringing the leads together, and an open, ambiguous, but hopeful ending (nearly identical).

While completely different in plot and setting, there are some interesting similarities. Both FLs end up in a "different world" (traveling in time vs. entering a shadowy world of assassins) where they meet the ML. Both MLs are played by the same actor, and are both kind and quiet characters. Both dramas feature a focus on umbrellas and have a more unique tone and "look". The endings of both, and the ML's fate is open-ended and ambiguous but hopeful.

School setting, sweet relationship between leads, ML is a good student and tutoring FL who is a poorer student. Their personalities are somewhat similar.

Both feature time slip time travel where ML and FL can travel to each other's time, subtly influencing and changing events.