What is the difference between 100 percent alcohol and absolute alcohol?

100% pure ethanol is 200 proof. vodka is distilled until it is almost totally pure alcohol and then cut with water to give it its final alcohol content and unique flavour, depending on the source of the water.

absolute alcohol n.
Ethyl alcohol containing no more than one percent water.


Chemists may buy absolute (200 proof, 100% pure) ethanol, and though absolute vodka is nowhere near 200 proof, I assume that's where they got the name from