Both really good, high quality/production level dramas, with interesting characters and relationships, character developments (not only ML but also female leads).
Not quite similar plot but has many similarities:

*kind hearted, nice, "always smiling" ML whose life and personality changes because of actions female (in MFS it's FL who loves him but he doesn't, in TIM it's SFL who is ML's gf and he loves her very much)
*after those events, ML's changing and few years, he is very mad at this female and wants revenge.
*ML's revenge involves/is against FL
*FL loves ML much earlier when he first loved SFL and approximately half of the drama doesn't love FL

in both:
*FL is famous celebrity
*ML becomes bodyguard
*love/hate relationship

A love to kill is much better also dark drama.
If you liked this things in Nang Rai Tee Rak you can try this Kdrama.
Though I'm not sure if after "love to kill" it's proper recommendation (these dramas are on different level).

quite similar plot/romance
*mafia boss falls for young student girl
*big age gap
*father of this girl is in debt with ML (mafia boss)
*at some point ML offers FL sex for debt
*ML has soft feelings for FL but often behaves rude/mafia style (he is more rude in Morrasoom Sawat)
*there is another boy (SML), younger who is interested in FL
*FL is quite strong, stubborn in korean drama, on the opposite in Tai lakorn, she is weak and let's be honest - stupid
*Overall neither of these dramas are high quality or good, but Korean is much better

*Both dramas focus on teenage girl, who is very significant person, active, funny, smart, kind, hilarious vital and full of life.
*In both drama FL develops attachment on much older teacher/mentor (ML), in "Hello mr. Right" it's romantic crush, in "Nang Ai" playful cute thing, which will make ML fall for her deeply.
*Both story develops in learning institution and have overall same vibe, light and good watch.

Both dramas involve a fair amount of action and an interesting plot, with romance. lots of twist and turns, plot when you never know what happens next.

Romance has somehow similar feel, man madly in love with woman and doing whatever it takes to get her back (there are more details similar, but I'm trying not to say spoilers), he never gives up on her though he has much reasons for it. So if you liked one, you would appreciate another, (I'm talking about main romance of MBB and anti hero SML's romance in Giant, which is best part of Giant )

For my taste romance in Giant was better, though overall as drama MBB was better.

both have similar situations: politic, powerful people behind scenes, puppet politicians, agents, conspiracy, power struggle, enemies and allies ... multilayered characters and unexpected situations/story developments, when you don't know who is whose enemy or ally, what will happen next...

in both dramas there are characters who you start hating/loving in the beginning but then change your mind, or often you just don't know are they good or bad.
also in both dramas we have "bad person" characters who are so smart, strong and charismatic we love/hate them....

overall both dramas are "multi mains", with many well developed characters, so we could say they are mains. neither of this dramas are one or two character shows, though in K2 we have more obvious male lead and he is above all.

both have strong women characters, though SFL in the K2 is incomparable.

both have little romance as side story (though in DS60D it's really side story and very little, when in K2 romance was forced to be more on front and I think it was main issue with that great drama)

****Main difference is: K2 has lots of actions and badass/physically fighting ML who is center of the show, so drama is somehow more "adventure". But if you liked K2 not only character K2, then this drama is also for you.

both:
*Historical
*very good bromances
*friends love same woman
*ML and SML at some point become rivals (especially in WBDS) but stay friends and love each other till the end
*you will have second male syndrome in both dramas, in TKIL he is very nice very good and loyal lovable guy, in WBDS he is anti hero super charismatic dark guy, star of the show. Both have sadness in their eyes...

Romance is very good in King in Love, and unpredictable love triangle, but in Warrior it is weak part, but bromance and SML is so good... both must watch dramas!

not so similar, but both have:
*love triangle, unpredictable who will FL choose. For viewer both guys are likable, of course you will ship FL with one (you like) but you will like/love/understand other guy too.
*good historical + romance dramas.
*ML and SML are/become friends,
*quite good side characters and interesting plot (other then romance).

both are really good dramas, not just "one more historical romance", in "Chuno" fight scenes are best I have ever seen, also very unusual charismatic ML, in "King in love" is very good bromance and romance!

not so similar, both are very good and quite unique dramas, hard to recommend something very similar, but both:
*about good friendship and same time love triangle between friends.
*both dramas have rare unpredictable love triangle, when you can't guess who will FL choose. Also, for viewer both guys are likable, even though we always choose one and ship FL with him, in these dramas, you will like/love/understand other guy too.
*period dramas (one historical, Goryeo period, second 80s),
*quite positive feel and nice watch.
*very beautiful cinematography.

totally different story/genre/feel, but I recommend because both have same rare situation in romance part.
(spoiler):
If you liked story line where FL loves man even knowing he is gay, and that man also loves her, is friend and support for her, cares for her, but of course different way, he romantically loved other man, but now tries to be man/husband for her; also there is another man who loves FL... then you should try second drama too.

SB is more drama, intense plot, revenge and serious vibe, Hyena in more light and more romance focused

both dramas have similar vibe and stories are kind of similar too.
in both dramas ML are similar type and he wants revenge ( a nobody against a big corrupted company).
anti heros/villains are similar too, even visually, young rich spoiled guy with high ambitious and questionable morality.
ML and anti hero are enemies and their war is quite similar in both dramas.
spoiler:
ML goes in prison in both dramas.
romances have also similarities, ML and antihero love same girl. after some time one of them moves on and falls for another girl (sister of his enemy)

Overall themes are different but romance vibe, chemistry and relationship between ML/FL are similar:

*age gap (older woman)
*ML was in love/adored her for 10 years,
*ML adores her so much and actor plays that so good, he looks at her with such eyes... chemistry is so strong (mostly because of ML and his facial expressions)
*FL is linked to big/emotional moment for ML when he was child/teen, after that she becomes his kind of idol and purpose, after that for long time (10 years) he wants and dreams to meet her and be with her, be equal with her.
*FL is really strong woman, independent, successful, quite individual (not standard strong FL)
*ML is young but quite mature, serious, priced and loved from people around him.
*though FL is strong woman, who doesn't much need to be protected by men, and ML is younger he anyway wants to protect her all the time, his biggest purpose is her wellbeing.
*for long time ML hides from FL how big was his crush for so long time, that h was thinking about her all the time for 10 years.