The Korean version is the original version. The Korean version is pretty funny, and the first episode of the Hong Kong version looks to be on a good track so far as well.

Both are college-based dramas where the couples interact both in and outside college. While Love Class Season 2 has three couples, Why R U? has two couples. Screentime is divided pretty neatly between the couples in both dramas. Some aspects of both dramas reminded me of each other.

Both deal with bullying and the aftermath of how it affected the main protagonists and their revenge plans.

Both dramas include male leads who have become cyborgs due to fatal injuries and their love stories with the female lead where they find out later that their love interest is part robot.

They have the same female lead. The vibe between the relationship, and the overall relationships between the main couple also gave similar feelings of almost cute giddiness because of how the relationships started out and went on throughout the dramas.

Both have main characters who heal each other, mainly from emotional isolation/loneliness. Both are melodramas that tug at your heartstrings.

They are supposed to be in the same fictional universe

They have a similar story relating to the princes and time travel. Moon Lovers is a bit darker drama.