Bump Up Business

Both have extremely similar storylines.
They both are about having to sort of pretend to be a couple for cameras, while also "disliking" each other.
One is about a long-popular actor being forced to co-star in a BL film with a rookie idol.
While another is about a popular idol being forced to play a BL couple for the fans with a trainee and soon-to-debut idol from his company.

both of series about industry, but bump up business is about two idols, when city of star is about famous actor and just a guy

Both are Romance shows about being K-pop idols. Dream High is about 6 students at Kirin Art High School dedicated to becoming Kpop idols. While they learn how to sing, dance, and write songs they start to develop feelings for one another.

Both shows are centered around idols and social media. Just like how Bump Up Business features K-pop group OnlyOneOf, Celebrity also features K-pop idols like Yuqi from (G)I-DLE, Minhyuk from CNBLUE, Junho from 2PM, Hyosung from Secret and Five Girls, Bora from Sistar, and more.

Both are Celebrity Romance shows but instead of K-pop idols the main character, Han Sekye is a top actress.

I feel like they kinda give off the same vibe. Both are BLs about Fan Culture, the Entertainment Industry, and Social Media.

Both of these Korean BL's are very character-driven stories (the story is focused on character and relationship development, rather than a plot/the story is carried forward by characters rather than plot events) about young men pursuing helping each other pursue their overlapping dreams of fame.