A distinguishing characteristic of one-act plays compared to full-length plays is their brevity and focused narrative. One-act plays typically consist of a single act, often ranging from 10 to 30 minutes, concentrating on a specific theme or moment, while full-length plays often have multiple acts and more complex storylines. This brevity allows for a quick, intense exploration of characters and situations, making one-act plays ideal for showcasing concise storytelling and immediate emotional impact.