Suspense is the "slow-burn" of storytelling—a lingering feeling of anxious uncertainty about what might happen next. While is a puzzle about a crime that already happened, and surprise is a sudden shock, suspense is the visceral experience of waiting for a known or suspected danger to strike. The Mechanics of Suspense
Suspense Writing: Examples and Devices for Tenser Stories - NN Suspense
As Alfred Hitchcock famously explained, true suspense occurs when the audience knows a bomb is about to go off, but the characters do not. Writers build tension by "bread-crumbing" information
Writers build tension by "bread-crumbing" information, revealing just enough to keep you guessing but withholding the final resolution until the climax. Key Elements of a Solid Thriller and surprise is a sudden shock
Suspense thrives when the reader has more information than the protagonist, creating a "double vision" where you want to shout a warning to the characters.