Both shows pit the ML against a cult:
>> In SM2 the ML is an ex-con who is trying to save/help his townsmen from a religious group who are really aiming to take away their money.
>> In Trap, both the ML (detective) and the FL (criminal profiler) discover and try to take down a cult/group of serial killers.

Both shows pit the ML against a cult:
>> In SM2 the ML is trying to save/help his townsmen from a religious group who are really aiming to take away their money.
>> In Voice 3, both the ML and the FL try to take down a cult leader who is grooming kids and turning them into serial killers. This is a sequel for Voice 2, although the FL looses A LOT of relevance.

Both shows pit the ML against a cult:
>> In SM2 the ML is trying to save/help his townsmen from a religious group who are really aiming to take away their money.
>> In Voice 2, both the ML and the FL discover and try to take down a cult/group of serial killers.

In Both shows:

>The Female Leads similar in attitude and their interactions with the MLs are similar as well. With her dictating what the ML should do in order to sell "their (pretend) relationship" to other people.
> The MLs are serious but really nice people.
> MLs' ex return and create a love triangle.
> The MLs bend over backward for the FLs.
> They end up cohabitating.
> They pretend they have a relationship in front of other people.

While LWF focus is on the childhood connection and the misunderstanding that tore apart the main leads, MND is more about two people striking a deal (pretending to be together) in order to get people off of their back. Having said that, both shows share some commonalities, such as:
> The plots are light-hearted and not to be taken seriously.
> The characters are eccentric.
> Both show a love triangle involving two guys trying to get one girl.
> Family is an important component of the show.
> The leads don't like each other at first (hate to love trope).
> Leads develop a friendship.
> The FL doesn't care how she comes across.
> The ML suffers from a childhood trauma.

In both shows:
> One of the leads is able to see ghosts while the other lead is a supernatural being.
> Deal with ghosts.
> One of the leads discover things about their past.
> There's a childhood connection between the leads.
> Art direction is top-notch in both shows.
> Both shows have similar endings, albeit Hotel del Luna's is better put together.

Some differences to highlight:
> Whereas Hotel Del Luna has a more episodic feel to it (helping a different ghost each episode), Black weaves all of the episodes together in a big and intricate web. Which means that every episode is about "one same story".
> Black is darker than Hotel del Luna as the drama ventures into the second half.

In both shows:
> The ML is adorable and a bit of a dork.
> The FL can protect herself in a fight (and the ML, for that matter!)
> One of the leads is reckless while the other is a bit more cool-headed.
> Both leads follow their moral compass, but one of the leads ends up stepping over the line in their search for justice.
> The leads work to stop a psychopathic serial killer.
> FL suffered a loss at the hands of the psychopath.
> Both share a similar issue/tragedy.
> There's a lovable team of misfits trying to stop a big threat.

In both shows:
> There is more intrigue than action.
> Corruption runs rampant.
> The leads band together against a common goal.
> The ML suffers a betrayal.
> The FL discovers a secret regarding her father.
> Similar atmosphere (art direction).
> The plot involves the kidnapping of someone.
> The higher ups attempt to stop the ML (detective) of TLW; the higher-ups attempt to stop the FL (Proscutor) of Justice.

Both shows:
> Have a ML who's trying to unravel a mystery involving them and their loved ones.
> The leads reluctantly start working together, but then they grow to care and rely on each other.
> The FLs are agents (one is a detective, the other a NIS agent).
> FLs are one of the few who believe in the ML.
> The show is action-oriented with a side of romance.
> Who the "big baddies" are is predictable.
> There are a bunch of mini antagonists along the way.
> Corruption is rampant.
> Have a group of misfits banding together to stop the big bads.

Both shows:
> Have adorable male leads who are good at heart.
> Smart and mature female leads who are the apple of the male lead's eye.
> The male leads end up bringing hope to the female lead.
> The relationship between the leads is very balanced.
> There's a big focus on romance and romantic moments/gestures; more so in TTON.
> Both male leads pretend to be someone else at first (deceiving the female lead) but for a good reason.
> The Female Lead is caught between the affections of the male and second male leads.
> Male Leads are seen as an obstacle by the second male leads, who desire to kill them.
> Male Leads do not want to sit on the throne.
> Male Leads try to keep their families safe.
> The cinematography is beautiful!

Both shows:
> Focused heavy on the relationship of two brothers (one of them blood-related, the other sworn brothers). That relationship, however, becomes rocky as the brothers find themselves fighting on different sides; ending up meeting each other in battle.
> The Second Male Lead (one of the brothers) ends up struggling to find their place and, as a result, face plenty of identity crisis. Their painful journey is very heartwrenching, but the result is that they end up stealing the show with their amazing performances.
> Have an antagonistic parental figure.
> Female leads are good, but their impact and contribution to the show is minimal.
> Have a small side-plot of romance.
> Male Leads end up going to war and finding a click, becoming the leader of their group of misfits.
> Second Male Leads end up going to war and struggle not to be stabbed in the back. They end up losing hope, but attain one loyal man (their sidekick).
> Male Leads end up giving their loyalty to a man who's trying to change the nation.

Both shows:
> Are action-oriented.
> Have adorable male leads who can hold their own in a fight.
> Have strong and nurturing female leads.
> Have leads establish a balanced relationship; healthy, nurturing, honest and reliable.
> Main leads show a lot of chemistry.
> Have leads focused on getting justice, more than revenge.
> The Male Lead lost a loved one.
> Are part of a team of misfits.
> Antagonists hold power through corruption.
> They face a number of antagonists, some of which are portrayed a bit cartoony.