- both dramas are set in the republic period
- both dramas arguably feature a bromance
- both dramas deal with mysteries

however, Tientsin mystic has supernatural elements in it, and imo the mysteries are more interesting because of that. both dramas have lots of smaller mysteries and a bigger conspiracy behind the events.

Tientsin Mystic is a bit of a darker drama though.

Both feature strong female leads that are intelligent and cunning. The storyline is really different and Young Blood is (in my opinion) a smarter drama, but the female leads are somewhat similar.