"In a mystery, the crime has already been committed, but the hero and the reader must figure out by whom. In a thriller, the crime (at least the biggie) hasn't been committed yet, but the reader knows who the bad guy is; the question is whether he can be stopped.”
-Allan Leverone, bestselling author of thrillers and mysteries.
In thinking about the differences between Thrillers and Mysteries, I have a few more to add.
"Characters in Emily Hanlon's Petersburg carry conviction... The scenes of passion, plotting, violence in the streets and confrontations with the dreaded secret police succeed each other at a mounting pace."
— The Literary Guild