All good, I first internalized the difference for real after playing Kerbal Space Program. It starts off measuring your velocity relative to the surface, where 0 meters per second means you're not moving with respect to the ground. But get high up enough and it measures your speed by how fast you actually go around the planet, not respective of the spin. It makes a huge difference for space travel. *A geostationary satellite is traveling at some orbital velocity but its surface velocity would be zero.