Recommendations

Both of the series central theme is a strong female lead character seeking and executing revenge. ..

Both deal with time travel/time dimension hopping

Both have ML in Police/Detective work

Parents love for their child is shown here/Both influence our ML

The three main characters (ML/2nd ML/FL) are all connected to each other like Tunnel

Both Family/Human Sci-Fi Drama

They both tell the story of two persons who knew each other before, got separated but have now reconnected. Where the Lost Ones Go is more of a entertaining reflection of how we change and grow, whilst Love is Sweet brings more comedy to the table. The main leads have great chemistry in both series, though I do believe the chemistry in Love is Sweet is unmatchable.

Both female leads were having an affair with a married man with whom they work in the same place. They are both seeing the man but they don't really love them they started falling in love for real with the male lead.
both are Romance and I think moth are mature

Male lead is a general who is extremely cold with a fearsome name to the public. Female lead is streetwise, active, cute and funny. Despite being fearful of the general initially, both ML and FL fall in love with each other.

Both dramas have the same FL and she is strong and powerful in both dramas.
Both MLs would die for her. Great fighting scenes, Especially in Legend of fu Yao.
Powerful MLs in both dramas. I must say the plots and costumes and set designs is better in Legend of Fu Yao. Great romantic scene in both.
( You would love it)
Great chemistry in both. ML is more playful in Legend of fu Yao while in Eternal love ML is more serious and gentle.
Both these dramas are my top favourite Chinese dramas. Master peace.

Similar, historical romance comedy type of drama. Although they may be similar each historical drama don't really have the same concept, mostly.

Similar vibes. Different story though. Revenge, infidelity and thriller. It is done really well and is as exciting and intense as TWOTM. A shorter drama but it packs it in. Great OST!

Both are Gumiho dramas. In Tale of Nine-tailed, ML is a Nine-tailed Gumiho. In My Girlfriend is Gumiho, FL is a Gumiho. Both showcase a sweet love story between the leads.

1. MLs are immortals. In Nine-tailed, ML is a gumiho. In YWCFS, ML is an alien.
2. MLs are waiting for his first love (which turned out to be FLs) from Joseon Dynasty.

These two share a lot of similar concept. Both MLs are immortal with supernatural power. ML met first FL when FL was still a child, in Nine-tailed: ML saved FL, in Hwayugi, FL free ML from his prison.

Similarities:
- The leads are childhood friends
- The FL in SIL used to bully ML and the ML in LIS used to bully FL in their childhood.
- Their chemistry is awesome. (It is the main thing that kept me going)
- Separated due to a misunderstanding.( In childhood)
- Love×Hate relationship.
Difference:
- SIL is a collage romcom, LIS is an Office romance

If you like childhood friends romance, then you may give it a try..

Similarities-
- Plotline - the 1000 yr old fox who is looking for his woman to be reincarnated
- ML who is someone who gives up responsibilities and is living like a vigilant
- Female Lead works in news industry: In M&V she is an aspiring journalist whereas in TTONT she is an Director for TV show
- SML is ML's Brother who keeps killing people and annoying ML
- common mythical references : liver eating, summer rain, blindness, one love etc
Differences
- M&V is more of romance centric whereas TTONT is mix of action, investigation, and horror
- FL is a lot stronger character in TTONT

The both have a spooky-like style and involves supernatural creatures (Hotel Del Luna involves ghost and the afterlife world while Tail of the Nine-Tailed deals more with mythological creatures such as the foxes, etc.).
The male lead of Tale of the Nine-Tailed and the FL of Hotel Del Lune both are more than 1000 years old and have a past that ties with someone important that they have lost.
Also the concepts of reincarnation and past lifetimes are an overarching theme in both shows.

1) Both include supernatural beings (Gumiho / fox spirit) as the male lead
2) Both of them have romance, humor, hidden identity & re birth
While Tale of nine tailed takes place mostly in the modern world, Gu Family book is set in the historical era.