Both dramas are,
- Korean BLs
- kinda same vibe
- lightweight & short(though STCO is relatively long)
- high-school crush

Both are korean BL
Both have cute actors
Nice plots

Both are Korean Boy Love Series adapted from Web series.
Both are around same length.

both are korean BL dramas.
both are adapted from web series.
both are around same length in time.

- Both are BL dramas.
- hate to love relationship
- both are superhit dramas
- attractive actors and lovely storyline

SPECIAL SIMILARITY :- BOTH DRAMAS ARE HARD TO FORGET.