What is the difference between a swirl mark, a scratch and clear-coat etching?

Swirl marks are usually clusters of very fine scratches that appear as circular spider-web patterns under direct light. A scratch is a more distinct line in the paint that can vary greatly in depth. Etching is a depression or chemical mark in the surface caused by contaminants such as minerals, bird droppings or chemicals rather than by physical dragging. Each responds differently to polishing, so identifying which one you have comes first.