The difference between tension and suspense

Writers talk about tension and suspense as if they're the same lever, turned up or down together. They aren't. The two come from different mechanics, and a scene that reaches for the wrong one usually ends up frantic or flat instead of gripping. Knowing which one a scene actually needs lets you build it on purpose instead of hoping it works.

Suspense runs on what the reader knows

Suspense depends on a gap between what the reader knows and what the character knows. The reader holds information the character doesn't, or the character is holding something the reader is waiting to see revealed, and that gap is what pulls the reader forward. Hitchcock's bomb-under-the-table example still explains this better than most craft books manage. Two people talk at a café table while a bomb ticks beneath it. If the audience doesn't know the bomb is there, the scene is small talk. Once the audience knows, every ordinary line of dialogue becomes unbearable, not because the words changed but because the reader is now carrying information the characters lack. The gap is the entire mechanism.

This is why suspense has to be planned rather than written in the moment. You can't generate the feeling inside the scene where it pays off; you have to seed the information earlier so the reader is carrying it when the scene arrives. A gun mentioned three chapters back. A letter the protagonist still hasn't opened. Suspense is built backward even though it's felt forward: the reader dreads what's coming because you told them, quietly, what was coming.

Tension runs on what's unresolved right now

Tension doesn't need a secret. It needs two people, or a person and their own competing wants, pulling in different directions inside the same scene, with neither side willing to yield. A negotiation where both parties need the deal but can't admit it. A conversation between siblings where one is trying to apologize and the other won't let the apology land. There's no hidden bomb and no future payoff. Just two people who want incompatible things, forced to keep talking in the same room.

This is why tension can be built purely through dialogue and blocking, with no plot machinery at all. Two characters with incompatible wants, given nowhere to go, will generate tension on the page even when the reader knows exactly as much as they do. Take away the exit and the pressure compounds.

The two often coexist in the same scene. A conversation between people who no longer trust each other carries tension on its own; add the reader's awareness that one of them is armed and you've layered suspense over it. But they aren't interchangeable, and treating 'raise the stakes' as a single dial usually means both are being turned halfway when neither reaches full pressure.

Suspense beat
  Reader knows: the letter in her coat pocket is a rejection
  Character knows: nothing
  Scene: she makes coffee, argues with her sister about dinner
  Effect: an ordinary scene carrying extraordinary dread

Tension beat
  Reader knows: exactly what the characters know
  Both characters know: neither will admit they're leaving
  Scene: they pack the same box for two different reasons
  Effect: unresolved conflict, no secret required

Writing each on purpose

For suspense, decide what the reader needs to know before the scene starts and plant it earlier, clearly enough that they remember it without a reminder mid-scene. Then write the surface of the scene almost flat. Ordinary dialogue over a hidden threat does more work than dialogue that keeps gesturing at the threat it's sitting on.

For tension, strip the exposition out and let the conflict live in subtext. Characters rarely say what they actually want. Let both people say something adjacent to the truth and let the reader feel the distance between the words and the want. The line where a character explains their own motive out loud is usually the line that kills the tension a scene had been building.

The distinction matters most at revision. If a scene feels inert, ask which one it's missing rather than reaching for both at once. A scene with no live conflict between the people in the room needs tension, and no ticking clock will fix that on its own. A scene where the conflict is already live but nothing is being withheld from the reader is probably fine as it stands; it was never a suspense scene, so stop trying to make it one.

When a whole act reads flat, it's usually easier to see why once the scenes are laid out side by side rather than scrolled through one at a time. Chaptered's corkboard view puts a project's scenes on cards across the act, which makes it fast to spot a run of scenes that are all tension and no suspense, or the reverse, before it becomes the reader's problem.