Both dramas involve accidental time traveling and falling in love with a Joseon man. Splash Splash Love is only 2 episodes long, while Queen In Hyun's Man is a full length drama.

Both dramas involve accidental time traveling and falling in love with a Joseon king. Both also deal with former lives/ reincarnation. Rooftop Prince is a full length drama (20 episodes), while Splash Splash Love is a Drama Special (2 episodes only). Both also star kpop idol male leads (who are should be considered fantastic actors).

Both are about girls who are a bit out of place in their new environments and just happen to befriend and fall in love with rich and powerful people. Moon River takes place in a university, while Boss & Me is at a workplace.
Both are romantic comedies...but have drama in various episodes.