The defibrillators used by paramedics on ambulances, in hospital settings, and the ones you typically see on TV are manual defibrillators. They are larger than AEDs, require interpretation of the heart rhythm by a trained operator, and must be charged and discharged manually.
AEDs are smaller, computerised devices designed for use by any bystander. They analyse the heart rhythm automatically, decide whether a shock is needed, and guide the user through every step with audio and visual prompts. They will not deliver a shock unless one is required.