Both:

1. Legal dramas that show the audience how the system in South Korea works: IHYV with public defenders and WYWS with prosecutors.
2. Have leads with lives tied together by a past tragedy.
3. Involve flawed people trying their best to help others in an imperfect situation.
4. Feature love triangles with a nice SML
5. Use supernatural powers to help solve cases.

The main difference is WYWS is an episodic show that focuses on the leads and their ability while IHYV is a complex revenge cycle that involves most of the characters in the main plot by the end. They also have different romances: WYWS is quick, light and cute with a bit of tragedy while IHYV is a slow burn big love, big obstacles and big payoff.

1. Both noona romances where ML loved FL for years but has to adjust to the reality of her as a person and FL realizes her feelings for ML are romantic and not friendship.
2. Both have a cute, heartwarming cohabitation romcom as a main feature.
3. Both have a love triangle in a slow burn romance.

So the relationship will feel similar in the beginning. But the genres are different and while Romance is a Bonus Book stays chill and slice of life in I Hear Your Voice it's mostly the romance that's slice of life and the rest of a story is an epic revenge thriller that plays out through court cases. It'll make you laugh, cry and constantly google info about the South Korean legal system. Recommended if you're looking for something more edge of your seat with a sweet noona romance to keep you hooked.