A mystery is about solving a crime or a puzzle. The protagonist’s goal is to uncover the clues, solve the mystery and bring the antagonist to justice. Typically, the crime happens near the beginning of the story the identity of the antagonist (murderer) is not revealed until the end. Examples include Agatha Christie, Murder She Wrote and Psych. source
Types of mystery listed here include detective fiction, police procedurals, cozy mysteries, noir, caper, and historical mystery.
Dark academia " features an academic setting, like a college or boarding school, and usually features some kind of a dark twist. Hence dark academia. Another description focuses on its themes: a focus on the pursuit of knowledge, and an exploration of death and morbidity." source
A suspense novel is about suspense. The reader knows the protagonist is endangered from the start, but the protagonist may only gradually become aware of the danger. The suspense genre covers everything from romantic suspense to psychological suspense and horror. Examples include Nora Roberts, Lynette Eason and Alfred Hitchcock movies.
A thriller is about action and danger. The protagonist’s goal is to stop the bad guy’s evil plan from succeeding. The protagonist and/or others are in danger from the start. Thrillers come in a wide variety of subgenres, including: espionage, political, legal, eco-terror, disaster, treasure, and sci-fi. Big names include Tom Clancy, John Grisham, and Clive Cussler. source
For more information, click on the following guides: