Thriller and mystery are of course high level genres, there are many sub-genres in both categories. For example Psychological Thriller or Cozy Mystery. There are lots more, so when considering Thriller vs Mystery in this post, I'm just looking at the broad, high level classification.
I'll share some definitions I've found then let's chat. Why do these genres to get so interchangeably used? Can a book be both a thriller and mystery at the same time?
A thriller is a fast-paced novel full of conflict, tension, suspense, unexpected twists, and high stakes. Every single scene and element in a thriller is meant to propel the action forward, test the characters, and take the readers on a roller coaster ride that will leave them on the edge of their seats.