Dream High (2011)

They both are centred around a bunch of teens training to be idols with a bit of romance involve too

Kiki Inoue works part-time at a convenience store, spending the better part of her day lazing about or reviewing sweets on her social media account. One day at work, she is introduced to the chain’s CEO, Takumi Asaba, who, as it turns out, is familiar with Inoue’s online reviews. Asaba asks Inoue to develop new desserts to sell chain-wide. As CEO, Asaba is tasked with turning around the chain’s fortunes, as it is now ranked the lowest among its competitors. Close collaboration leads Inoue and Asaba to become sweet on each other.

Both drama's revolve around a musical theme, and the love of music that they share together. They also has wonderful soundtracks.

Both dramas are set in a music and arts school. The students take Zanto and dance lessons. Both dramas show the love developments between students and their relationship with adults.

Both are KBS dramas. They have an older mentor that tries to make the students dreams come true. For dream high its musical aspirations and for G.O.S. its College aspirations. Both have drama between the students when it comes to relationships.

Both dramas deal with music, friendship, and competition. Both have a lot of kpop references.