Based on episode 1 - Both dramas have a similar fantasy genre/cinematography/atmosphere. If you liked Arthdal Chronicles you may also like the style of these 2 dramas.

Both dramas are addictive with greedy villain FLs and main characters want to get revenge for their loved ones.
Uhm Hyun Kyung was the FL in both dramas and there is a similar plot twist (spoiler)
Kim Hee Jung was also in AMIAV before as a villain but now she is a good supporting character.

- both FLs grew up as orphans and both mothers are villains
- both dramas have hit and run incident in the beginning episodes
- in GG her identity was stolen but in RS she was abandoned, they could've had the chaebol life that the 2nd FL has in their place instead of them

Both female leads have self esteem issues and skin problems on their faces. Both male leads are handsome and fall for the FLs despite their appearances.

Both dramas have exaggerating/over the top humor and Ahn Se Ha is in both of them as a supporting character.

Both villains Min Jung and Yoo Ra grew up in a poor family and are greedy for wealth/status, and their moms also help them with their lies. Both FLs raises the baby that they abandoned so they could marry a rich guy. The ML in A Man in a Veil is similar to Ji Sang's character, he wants revenge since Yoo Ra caused his mom's death and Min Jung caused JS' dad to die. Min Jung and Yoo Ra blackmails the villain moms with their secrets from the past later on.

In both movies the main leads switches bodies with each other through a car accident, except in Reon the man's body is in a coma throughout most of the movie

Zombie Detective eps 5-8 has a cult similar to Save Me, the main leads work together to find/save a missing girl in the cult.

The style of slapstick humor is similar, and both use some references to other dramas/movies & cameos/guest actors in every episode

Both male leads have a hidden identity and are good at fighting. Both second leading males are obsessed with the female lead and want to hunt down the male lead.

In both dramas the main leading characters have the power to see how a person dies. Both are thrillers where the main leads work together

- Both are crack-addictive makjang dramas with over-the-top/persistent villains and family mysteries/pasts
- The female leads are naive and trusting of villains at first but they both become stronger characters later
- Both male leads have a transformation in looks (one would be from weight loss but the other is plastic surgery) and are given a new identity
- There is little romance in both but the scenes are satisfying to watch
- Both male villains (Lee Hyuk, Kim Nam Joon) are obsessed with the female leads
- Some characters and situations are somewhat similar in a way (but may be spoilers listing them)
- Both dramas have kind-hearted grandmas