What is the fundamental difference between a Remote Operated Vehicle (ROV) and an Autonomous Underwater Vehicle (AUV)?

To put it simply, an ROV is like an advanced "underwater kite" that you can only operate by holding its line (tether) from a boat. This tether is crucial; it not only powers the robot but also allows you to see real-time camera footage. You then control it with a joystick, much like playing a video game, ensuring it goes exactly where you direct it, and you can even manipulate its robotic arm to grab objects. Therefore, there's always someone "piloting" an ROV.

An AUV, on the other hand, is a "lone wolf." Before it goes into the water, you program it with a detailed plan, for example, "go to this area, make 5 passes, survey the seabed topography, and then return on your own." Once deployed, it executes the mission autonomously according to its programming, and you cannot control it in real-time during the process. It doesn't have that long "kite string," giving it freedom of movement and the ability to travel long distances. Only after it completes its work and returns can you retrieve the data it collected.

So, the fundamental difference is: an ROV is continuously operated by a human in real-time, while an AUV completes its mission independently after being programmed. One is tethered, one is wireless; one is constantly managed by a human, while the other is "free-roaming" underwater.