Antifreeze and coolant are essentially the same thing. The Automobile Association (U.K.) uses the terms interchangeably or together (coolant/antifreeze). Antifreeze is colloquial for the chemical fluid ethylene glycol. Ethylene glycol and distilled water, in equal proportions, are added to radiators to cool automobile engines in summer and prevent freezing in winter.
Ethylene glycol comes in various colors depending on the manufacturer and its use dates back to the 1930s. It produces basically two types of antifreeze: extended life and standard, the latter being more common. The coloration has to do with the kind of rust inhibitors and additives used. Propylene glycol has been introduced as a less hazardous alternative to ethylene glycol, but it is much more expensive and manufacturers have shown reluctance to make the switch, as of 2014.
Since car manufacturers use different types and colors, it is important to check the owner’s manual for the specific type of antifreeze in your vehicle. Whether it is called antifreeze or coolant, the mixture of water and glycol is absolutely essential to the operation of an engine by preventing freezing and corrosion and stabilizing performance at high temperatures. Approximately 60 percent of all engine failures can be attributed to cooling system issues, according to AA.