Question: what is the difference between denatured ethanol and absolute ethanol?
Answer: Absolute ethanol is hygroscopic (it attracts water), so don't expect it to remain '100%' ethanol for long if it's left uncapped. Denatured ethanol (either 95% or absolute) contains additives (such as methanol and isopropanol) that render it unsafe to drink, and therefore exempt from certain beverage taxes.