Both dramas have undercover cops
Both dramas have undercover informant or agent who has a daughter little girl trying to protect
Both dramas have secret past of the main lead and suspicious alliance

Two dramas about undercover cops
two dramas have a cop with secret past
two dramas have police and drug cartel undercover missions

Both martial arts and cultivating dramas
Both have great friendships between the leads
Both have good fight scenes
Both angsty dramas full of adventure

Both dramas have great friendship
Both have amazing martial arts fights
both have amazing angst and whump

Same male lead
different criminal case
same production company
same action criminal genera
both are enjoyable to watch

Both are detective dramas
both have older younger friendship at odds between the leads
both have bromance

Both are detective dramas
both have bromance between two leads
both have psychological aspect in solving cases

Both are detective dramas
both have psychological aspect in solving cases
both have bromance between male leads

Both detective dramas
both have partnership between a detective and suspicious partner
both have male friendship

Both are detective dramas
both have male lead detective and kind of suspicious partner helping him solving cases
both have bromance

Both based on actual history
both have same historical era and same historical characters but different production and actors

Both are republican era dramas
Both dramas have romantic relationships and Slight Bromance
both deal with war an fighting the enemies