I don't know if Dan John came up with 'the hinge' and the hip displacement continuum, but I'll credit him since that's where I heard it first - the squat to a (stiff legged) deadlift; there's a continuum.
Think of an "athletic stance" - back straight, hips back slightly, knees slightly bent. From that position, do you sink the hips and flex the knees? Then it's a squat. From that position do the hips flex and move (primarily) backwards and the knees stay (relatively) static? Then it's a hinge.