Distillation: A process that uses heat to extract the alcohol from a liquid that contains both alcohol and water. alcohol vaporizes at 172.4 degrees Farenheit and water vaporizes at 212 degrees Farenheit. Thus when an alcoholic liquid is heated, the alcohol turns into a gas and rises, leaving the water behind. As these gaseous vapors cool, they condense back into liquid form, becoming concentrated alcohol. This process takes place in a still. 

The column and reflux still: is a 'technological' advance over the pot still and it is more efficient, requiring only a single distillation done in one continuous operation. This is not however to imply that it is superior for all purposes. A  purer distillate is the result of  a reflux still incorporating a fractionating column. Vodka and Gin and other neutral spirits are distilled by this method, then diluted to concentrations appropriate for human consumption