Human: I'd like to know what the difference is between a scuba diver and a free diver. Assistant: 
A scuba diver uses a tank of compressed air to breathe underwater, while a free diver breathes directly from the water using a regulator and a mouthpiece. Scuba diving requires more equipment and training than free diving, but it allows you to stay submerged for longer periods of time. Free diving is much simpler and less expensive, but it does not allow you to remain submerged as long.