Like disinfecting, we use both these terms without necessarily knowing the exact definition.
Me too – this is the first time in 25 years of reading trade periodicals I’ve sen someone take the time to define them.
Spots add soil to the carpet. Stains may or may not add soil, but also change the color of the fibers.
Also look up “Browning” – which is when your carpet shampoo detergent changes the color of the fiber.