Suspense/Thriller?

Don't overthink this. When applying to agencies that combine them, call it a suspense/thriller. If they separate them, pick one. It probably doesn't matter which one; they'll classify it the way they want anyway. And I'm willing to bet there aren't any agents who will turn up their noses at a thriller while accepting suspense and vice versa.

My 2 cents

Haven't ever heard of a suspense genre -- maybe they are referring to mysteries? Big difference between a mystery and a thriller is a mystery keeps it a mystery from the reader too. But I can't say I'm familiar enough with them.

I do want to sit down and read some Sherlock Holmes novels one day just out of curiosity. And I remember reading Encyclopedia Brown as a kid.

When I think of a suspense novel I think of something that scares you with silence. It is the lack of knowledge that terrifies like in The Silence of the Lambs by Thomas Harris. In a thriller I think of something that is meant to scare you through action like in I Know What You Did Last Summer by Lois Duncan. Then there can be novels that classify as both because they scare you with action and with silences.

Thrillers, which I write, have some bent relating to espionage. Then it seems to roam from there.

I wish I could remember where I saw this just last week, but there were something like 16 sub-genres (if that's the way it was phrased) for thrillers.

Most early-stage writers have difficulty defining genres (I know when I started that I did; matter of fact, still do).

Again, there is something out there that defines this and I'm sorry I can't remember where to find it. Perhaps others will know. But there are specific distinctions. However, like Judg said, I can't imagine an agent dissing a work because the genre isn't specified in pluperfect terms.

Truth be told, it doesn't matter so much to agents, because those who represent suspense also usually represent thrillers, and vice versa.

However, there is a subtle difference between the genres, and it's difficult to explain.

Generally, suspense is a fast-paced story that revolves around the danger to one or a handful of people -- the protagonist(s), usually, though there may be subplots that involve danger to the antagonist, minor characters, etcetera. It's almost right, but not quite, to say that suspense is more character-driven, because the personal stakes are more important.

Thrillers have bigger stakes. The danger in a thriller is typically a danger to large populations or the entire world: the aforementioned espionage that involves countries, natural disasters, man-made disasters, terrorist takeovers, deadly diseases, that sort of thing. The typical thriller will involve a higher level of technical detail, usually relating to the protagonist's profession (doctors in medical thrillers, spies in espionage thrillers, ranking officers in military thrillers, etcetera).

But -- you can usually getting away with calling it either, and agents don't seem to mind much. They'll relabel it for you, if necessary.

I've been studying this question myself, because I wrote what I called a thriller, but which might more properly be called a novel of suspense.

A typical thriller shows a group of people under imminent threat of destruction--a country, a town, the protagonist and family (and the family's often important). There are many subgenres of this type of story, as with medical, legal, political, romantic, and so forth. A novel of suspense typically poses a threat to the protagonist, and though the threat may involve death, it's more psychological--the terror that shadows contain, the fear of loss. Thrillers push things to the max, chapter after chapter--chases, mayhem, gunplay, for instance--whereas novels of suspense turn more on character and may be less "noisy." Think Hitchcock here, or Graham Greene.

But these distinctions are pretty gray. John Le Carre, IMO, writes thrillers that (sometimes) turn more on character than anything else. Courtroom thrillers may not have car chases. And so on.

A book that may be useful to you is How to Write Killer Fiction, by Carolyn Wheat. She contrasts mysteries and thrillers, which isn't quite what you're asking, and her analysis sometimes seems narrow, because she doesn't mention the past masters of either genre, only the present ones. But it's worth a look, and I learned a few things.

All that said, I had a long conversation an agent the other day, the most encouraging rejection I've ever had. He didn't take my thriller/suspense novel, but he did say that the distinction between those genres is immaterial. If the story and characters work, they work.