What is the difference between STW and SOG, Analogy and its use ?

What is the difference between STW and SOG? STW (Speed Through Water) measures a ship's speed relative to the surrounding water, typically using a speed log. It's about the ship's movement through the water. SOG (Speed Over Ground) measures the ship's speed relative to the Earth's surface, usually using GPS. It takes into account the effect of currents and tides, giving a more accurate picture of the ship's actual progress. Think of it like this: STW is how fast you're swimming, while SOG is how fast you're actually moving towards your destination, considering the water's flow.