Propylene glycol and ethylene glycol differ from one another in antifreeze in terms of both toxicity and performance effectiveness. While propylene glycol has relatively low toxicity, ethylene glycol has far better heat transfer qualities.

Glycol is an organic chemical molecule from the family of alcohols. The glycol molecule, which is another name for diol, has two hydroxyl groups connected to various carbon atoms. The chemical family of alcohols includes glycols.

Despite having numerous uses in a wide range of industries, such as in the production of resins, inks, and polyethylene terephthalate (ethylene glycol) and cosmetics and preservatives (propylene glycol), both substances are frequently used in antifreeze and coolant mixtures.

A pure base substance called ethylene or propylene glycol is used in antifreeze. A specialized inhibitor is occasionally added to some recipes to help prevent corrosion of the system metals.

Antifreeze has two functions: it lowers the freezing point of liquids in cooling systems and raises the boiling point of water. By doing this, an antifreeze solution helps avoid overheating problems and keeps cooling systems operating freely and free of ice buildup during cold weather.

The degree of toxicity is the primary distinction between ethylene and propylene glycol. Propylene glycol has a relatively low toxicity, which is why it is also used in cosmetics and personal care items, but ethylene glycol is deadly and needs to be treated carefully to minimize exposure to humans and animals.

Ethylene glycol has a lot of advantages over propylene glycol, especially in closed-loop systems where there is little chance of interaction with food. For instance, ethylene glycol is far more successful in preventing freeze point depression; hence, more propylene glycol would be needed to keep the same freeze point as ethylene. Additionally, ethylene glycol has superior heat transmission capabilities because of its decreased viscosity.
Depending on the purpose at hand and the possibility of unintentional contact with food, drinkable water, or human consumption, propylene or ethylene glycol may be used.

Propylene glycol, for instance, is used in the de-icing of airplanes to both remove ice and other contaminants from the aircraft as well as actively prevent the formation of snow and ice during the winter during times of heavy snowfall.
Several antifreeze products sold in supermarkets also include it. While ethylene glycol would be used in regulated industrial settings and closed systems.