Both of them have similar concepts of a middle-aged or elder person possessing or transforming into the body of a young man/woman and causing hilarity and confusion through that plot. Additionally, B1A4's Jinyoung stars in both the titles.

Much like the premise of ThamePo, Idol : The Coup is centered on a k-pop girl group which decides to have their final comeback before disbandment. Both (although ThamePo hasn't come out yet, I'm assuming based on trailers) focus on the hardships and struggles of being an idol.
Also, both feature a boygroup called MARS lol.

Both dramas resolve around classical music and a music academy. They both also tackle a plotline depicting characters who are passionate to achieving their dreams.

There are many similarities between the two plots. In Extraordinary You, the female lead finds out that she’s in a comic world where she’s a supporting character with less time to live. Meanwhile, in Romance of Tiger And Rose, the female lead is a screenwriter who accidentally somehow gets stuck in her own script world where, like Extraordinary You, she’s also a supporting character with less time to live.