Recommendations

Both dramas consist of world where human and ghost exist.
The male leads find themselves crossing the line between the human world and ghost world, helping the lost souls to find peace before they can go off to a better place. They're both fantasy filled with trilling events.

Both dramas have a time travel aspect and I feel like the reason as to why they time travel are very similar. *SPOILER ALERT* I wouldn't necessarily say this is a spoiler but, you know, just to be sure. I feel like the reason the characters in both dramas are experiencing time traveling is because it will help them realize what they value most in life and pursue it.
Both dramas are also focused on job occupations (though one is about doctors and the other is about police officers).

They have a similar kind of humor (though The Fiery Priest is more often and more exaggerated in use). Kim Nam Gil is the lead in both the dramas too but that's practically the only similarities.

orchestra them dramas
i personally didn't like IWHYS and i'm sure park eunbi won't disappoint me as always

they have the same vibe of performance ballet/ orchestra

Both are using this technique where characters are talking in front a camera, a nice technique to show where these characters are coming from. Sixteen and River's edge are both teen angst driven, the latter is just more messy, has older set of characters, and better acted.

Both involve detectives and time travelling. The mystery unfolds slowly, while keeping the audience on the edge of their seat with each episode. Parallel worlds infused in science-fiction and the genres of crime and thriller. If you liked Signal, you might greatly enjoy Alice.

The tone and the ill-fated relationship between the characters due to their intertwined pasts. Even though totally different setting and plot, both are heartbreaking dramas that will leave a long-lasting impression and still hurt when thinking about them long after one has finished watching them.

Both dramas deals with a divorced couple getting back together, both work in the same workplace and also have Lee Min Jung starring.

In both dramas, the main protagonist is a bit unsure about their feelings towards another woman. 'Lesbian awakening' may not fit perfectly, but the characters' acceptance of their own identity is depicted in a light and heartwarming way.

Sweet budding lesbian stories set in a school/university setting. Both have really nice cinematography and soundtrack and have a calm vibe - also, while they're just a quick watch, they never fail to touch your heart!

Lee joon gi is the male lead of both drama, the similarity isn't obvious but you have a mc who frequently gets himself into trouble by trying to shoulder everything by himself, and female lead who worries/cries about him, and due to misunderstanding, she questions his love.

Both leads are talent wannabes that ended up as paid mourners. One is in traditional Chinese funeral that portrayed the job as loud wailing while the other is Japanese setting which was more on delicate manner.

While they are different, i feel that you should watch TWG because it has the same feel of DW. Even thought TWG deals with time travel it has the same feel as as DW since it has a young man that need to dig deep and find that warrior in him.

both are very similar in terms of hero fighing over fate and in turn creating ripples that further complicates his course