What are some main visual differences between a 72 and 73 Charger? Are there differences in body lines, grilles, or rear tail panels?

My dad and I were driving down route 66 today and out of the corner of my eye I saw a Charger parked at a gas station that usually has some old muscle cars for sale. When I saw it, I called it out to be a 73 Charger because I thought I saw an Opera Window (it may have been a half vinyl top). My dad said he saw the car before and talked to the owner who said it was a 72 Charger. Anyway, I might drive back tomorrow to go look at it just to see. It was a light metallic green with a white top and retractable headlights.