Put simply there are two types of stills for the distillation of spirit.
Pot Still:
Commonly used in production of Cognac and Single malt, little has changed with this still for centuries. Consiting of a vessel, to which heat is applied, as the contents boil the vapours are collected and condensed in another vessel. Because alcohol boils at a lower temperature than water, the vapour collected has a higher concentration of alcohol.
Column Still:
Patented by Aeneas Coffey in 1831, the Column Still runs continuously, instead of batches. It operates like a series of pot stills, in the form or porous layers in a vertical tube. The vapour rises, and portions condense as each layer gets cooler.
Key Differences:
Column stills can produce a spirit of 96%, whilst a Pot Still man only reach 40-50% and may require additional distillations.
Column Still distillate is clean and pure, but lacks the rich oils nots of Pot Still distillate.