To be more precise "Freon" was a brand name of refrigerant, I think originally sold by Dupont. Pretty sure it's not sold anymore? There are many different types of refrigerants and they all have different properties, usually (if not always) a hydrocarbon which makes it a big no-no greenhouse gas that's highly regulated obv. Also many refrigerants are highly flammable and I believe original Freon was flammable as well. Some flammable refrigerants are used in lots of places, not auto-move though. Some systems can even use propane (very close in chemical properties) and was commercially used at some point long ago. I guess it's still even used as a secondary refrigeration circuit in camping refrigeration units, although I'm not sure how they work personally.

Most common automotive is R-134a but I think has been phased out with a backward compatible refrigerant recently.