FoxSpirit

both have themes like
- mafia
- money problems
- loan sharks
- death of family member
- main(s) who has fighting skills
- entertainment business (acting for Payback, boxing fights for Knock Out)
- an ex who caused problems and is now a rival
- enemies to secret lovers
- action and fight scenes

- one main had to get involved with the mafia and became a loan shark and his love interest is an equally morally grey enemy and they have prior history
- there is some revenge and rival team up undercover work
- it's dark, contains action scenes, betrayal and violence
- dips into the entertainment business at times (Payback a lot more)
- enemies to lovers

both have in common:

- main character named Sun is involved with the mafia
- people he loves get killed
- he swears to take revenge on those who are responsible
- infiltrates the rivaling side to do that
- but gets romantically / sexually involved with someone in there
- generally petty rough, dark, violent
- have action fight scenes
- secret, forbidden relationship
- main has an ex and the parting was very painful
- main couple do some fight trainings together
- kind of enemies to lovers
- explicit (partly rough) sex scenes

differences:

- PayBack takes also place in the film industry with shady, illegal elements
- main couple starts with power imbalance and sexual favors (so far based on episode 1 and trailer)
- Bangkok Boy stays in the mafia realms
- main couple is very hurt/comfort and pretty equal

(I am writing this while watching episode 2 of Soul Mate)

Both series so far have in common:

- ships are m/m and f/f (not sure yet for Soul Mate)
- characters are multilingual:
Soul Mate characters speak Japanese, Korean, English and German
The Bangkok Boy characters speak Thai, Korean and English
(with actors from Korea, Thailand, Japan + some German extras)
- Korean orphans moved to another country and learned the other mains language (with slight accents <3) but still speak Korean with their Korean fam and friends
- one main is into boxing, so some boxing matches will be shown
- both mains are athletic:
Soul Mate ice hockey player x professional boxer
The Bangkok Boy muay thai boxer x black belt level combat skills
- one main attempts suicide in the beginning but gets saved by the other one
- both are kinda depressed and stressed due to shitty life situations
- one main doesn't want to have anything to do with the other one at first but they get along very fast
- there are some shady businesses and crimes going on the mains are dragged into
- it can get rough and graphic

Both are japanese BL about a bit older, moody writer and his new assistant who only came to help because of some favor to pay back but it develops into something more sexual with feelings very quick.

The Novelist / The Pornographer has a lot of parts and some people are confused about the order, so here is how it aired:
1. The Novelist (season 1)
2. Mood Indigo (season 2) (some say to watch this first but it chronologically came after Novelist and contains the backstory of characters that you are not supposed to know yet in Novelist ok? it is mainly a prequel but also has parts that play after Novelist, so it is also a sequel)
3. Spring Life (short movie)
4. The Novelist / Pornographer: Playback (movie)
5. Continued Spring Life (also short movie)

both series with:

- 80s Hongkok mafia vibe
- BL (+ side GL in Bangkok Boy)
- about mafia clans / families fighting each other
- main theme is revenge for killed loved ones
- pretty violent and bloody sometimes
- twisted and angsty but with some fun bits between
- mains with opposite personalities
- lots of hurt / comfort
- horny
- some kids got adopted by a mafia boss
- poverty & wealth are a topic too

Both BL are about a couple where one partner has a mental condition that changes their personality temporarily (Dissociative identity disorder in Innocent, I guess amnesia in LYT?). One personality dislikes the boyfriend. But the boyfriend still tries to get along with both personalities and be supportive.

Innocent is bit rougher and more mature than Love you Teacher.

Both are pretty surreal, bit creepy, mysterious BL / queer series that put the main characters and audience in (intentionally) confusing situations where nobody is sure what's real and what not. There is also a bit of philosophical questing about life and morals.

They are pretty good brain challengers for those who love riddles and solving mysteries.

Both are Thai horror BL about ghosts, revengeful ghosts with tragic pasts, sort of time travel through flashbacks into different time periods, Thai religion and reincarnation are a topic as well.

Both are Thai horror BL with a young friend group. Both are playing in rural areas of Thailand with a strong religion / mythology touch to it.

Both are action BL that have:
- one of the mains as heir of a (maybe bit dubious) family business
- violence and murder attempts
- one saves the others life
- opposites attract
- family drama

Both uncensored, wuxia themed Chinese BL about a royal guy and an assassin.

(myatb used a production company from Thailand but is still Chinese. There are Chinese and Thai dubs for it)