Both shows have the same feel-good vibe with our main protagonists struggling to follow their dreams but who, little by little, make their way towards their goal. There's also an organic kind of friendship between them, though in FFMW the leads were good friends prior to the start of the drama, whereas with SU they are quickly becoming friends (though there's a bit of lying and pretending involved at the start).

In both shows:
> The ML has a secret identity and meets the FL under false pretenses.
> There's a past connection between the leads.
> The ML is a prominent fighter and wants to keep the FL safe.
> The ML's job always puts him in danger.
> The ML feels lonely and seeks solace in the FL.
> The FL decides to help the ML with his case/job/objective.

In both shows:
> One of the leads is an undercover agent. In TSWLM it's the ML and in Vagabond it's the FL.
> The leads team up to uncover the truth of a tragedy that affected one of them. In TSWML the tragedy involves the loss of a loved one for the FL, in Vagabond the ML loses a loved one.
> The lead with the hidden identity comes clean to the other lead, allowing them to work together.
> There are plenty of action and fight scenes.
> There is a love triangle involving the ML x FL x 2ML.

In both shows:
> The ML has a secret identity and meets the FL under false pretenses.
> There's a past connection between the leads.
> The ML is a prominent fighter and wants to keep the FL safe.
> The FL is actively involved in finding out the truth about the case at hand.

In both shows:
> The ML has a secret identity.
> There's a focus on company espionage.
> The Main Leads where in a relationship but something happened that made them separate at the start of the drama.
> The FLs are actively trying to seek the truth about the "dire fate" of someone they loved.
> There's a love triangle between the ML x FL x 2ML.

Both shows have a ton of similarities:
> Have a subtle romance between the leads.
> In ZD the ML becomes a detective while in TGD the ML is already a detective. Regardless, they are both detectives who handle cases.
> ML dies at the start of the drama but they remain in the land of the living. Part of the drama focuses on them looking for the reason they died.
> The FL has street smarts which gets them hired by the ML.
> The FL is the first to find out the ML's secret.
> The ML must fight their instincts in order to remain "human". In ZD he must fight against eating other humans while in TGD he must fight against becoming a vengeful spirit.
> The 2ML is a detective who is in love with the FL.

Both shows have the same premise of a the FL trying to escape an abusive husband by getting plastic surgery and running away.

However, in LMIH, the FL ends up with amnesia so she must remember who she is first. There's also children involved and, overall, it feels more "Hollywood" (with the FL reminding me of the movie "enough").

Whereas in LIS there are no children involved and the antagonist is a lot more complex and developed. The FL also displays signs of intense PTSD and the ML is a lot more flawed, in that he also feels overwhelmed by the situation (since he gave the FL his dead wife's face).

In both shows:
> The FL tries to flee from her abusive husband. In LMI she succeeds, while in LAL she ends up in prision.
> The FL loses her daughter and strives to recover her.
> The mother-in-law is treated as an adversary.
> The ML is nice, helpful, successful and divorced.

Both shows:
> Have a FL who has street smarts and who is reckless but very determined to achieve her goals.
> Leads know each other from childhood and, as such, establish a good rappot almost from the start.
> Both leads are shown to be struggling to find their footing at the start of the show.

In both shows:
-You get a lot of action and fun fight scenes.
-The leads fight against corruption.
-One of the leads is reckless and the other is more mature.
-There's romance weaved into the story unobstrusively.
-FL gets betrayed by someone she trusts, but who is also in a position of power.
-Story's plot is old-school in nature.
-The antagonists act a bit like caricatures.
-Teamwork is crucial.

Both shows:
-Involve a character being an NIS agent.
-Have a lot of great action scenes.
-Showcase a female agent working undercover.
-Has a subplot of romance on the side and something of a love triangle.
-ML has a bit of bromance with a support character.

Same creepy vibe throughout. ML keeps insisting something weird is going on, but people keep dismissing his worries. In both shows the ML is agressive but stubborn in his pursuit.

While SFH has a active FL who is involved in unraveling the mystery, SM2 has a more passive FL.

Both shows involve a cult who takes advantage of people and murders them.