The first answer is it doesn't really matter. These genre tags are simply there to serve as guides to make it easier to figure out which book a particular patron may enjoy better than another. If the patron wants to call it a mystery, but you think it is suspense, you do not need to correct the patron. Getting a book they would enjoy in their hands is the most important thing, not what genre they call it. For more on this issue, click here to read the post I wrote in 2011 where I laid out my opinions on the need for genre distinctions but also conceded their limitations.
The second answer is, although it doesn't matter, there are easy to distinguish differences between a mystery, a thriller, and a suspense novel. I know this because I have spent 8 years narrowing down the distinctions as I have taught them to my grad students. So, here are the short, sound bite definitions I have created over the years; definitions that takes great pains to narrowly define the genres:
A mystery is a story in which a crime--usually, but not always, a murder--has been committed, and the means, motive, and criminal are in doubt or unknown. This puzzle of “whodunit?” is presented to an investigator, either professional or amateur, who then tracks the investigation, gathers the clues, and solves the case. Readers require that these stories contain all of the necessary clues for the solving of the puzzle within its pages.
Suspense is a crime story which, as opposed to mystery, is not about the things that happen, but rather it is about everything that might happen. Suspense is about the building of tension, layer upon layer, as the hero tries to stop the villain. Nothing is more important than this tension, and much of the suspense story is spent carefully raising it one heart pumping notch at a time. Compressed time frames, prologues, the inclusion of the villain’s point of view, short chapters with cliffhanger endings, and plenty of plot twists are all staples of the genre meant to add to the building threat.
I was inspired to write this post and share my opinions on the topic by this week's Books on the Nightstand podcast entitled, "How to Distinguish Thriller from Mystery From Suspense." Use this link to access the full audio, but below, I have also copied the links and summary which they posted to their blog as a supplement their podcast.Thrillers are crime stories that center around a particular profession: espionage, law, and medicine are the most popular and numerous. These books provide fast paced stories with details and jargon of the profession and the potential dangers faced by those involved in it. Another common characteristic of this genre is the loner hero who operates under his own moral code in his fight against villains seeking absolute power.
This podcast comes from the book publishing side of the debate, so it is slightly different, but extremely useful. We need to know where the publishers are coming from in order to be able to place the books they are marketing into the correct reader's hands. The original appeared here. From their site:
Mysteries, Thrillers, Suspense – What’s the Difference? (8:53) What’s the difference indeed? It used to be that buyers for large chains made decisions where a book would end up in the store. While that still happens, the internet and book discovery sites like Goodreads give books more chances to be discovered outside of a mystery section. To get a definition of these kinds of books, Ann did some Googling and found a 2008 blog post by former literary agent (and now author) Nathan Bransford, in which he says:
Thrillers have action
Suspense has danger, but not necessarily action
Mysteries have mysteries, i.e., something you don’t know until the end.
It seems like a pretty good description to us. Literary agency Bookends also wrote a post (that very same day!) in which they said, “While … mysteries tend to be about solving the crime, suspense/thrillers tend to be about stopping a killer or crime. In other words, often we know who the killer is, it’s not necessarily a whodunnit, but now we must find him or find a way to stop him.”
Ann recently received a new Scandinavian mystery called Midwinter Blood which is subtitled “A Thriller,” whereas Jo Nesbo’s books say “A Novel.” Will they reach different audiences because of the subtitle?
Finally, a recent Flavorwire post titled 11 Thrilling Books for People Who Don’t Read Thrillers, included Tana French’s latest Broken Harbor and Donna Tartt’s The Secret History.