Cognac is produced from the Ugni Blanc white grape variety exclusively, while Armagnac is produced from 10 different varieties of grapes fixed by the AOC, including the Ugni Blanc. The diversity of the grape varieties found in Armagnac is due to the winemaking tradition in the region, which also produces a wine meant for consommation. The Cognac region only produces wines meant for distillation.
Armagnac and Cognac are also differentiated by the still used in the distillation process.
The “armagnacais” still (please see above for the definition of an “armagnacais” still) features copper columns and provides a continuous distillation. (please see above for the definition of an “armagnacais” still) The “Cognac” or “Charentais” still features a basic design, made from copper. It uses a double heating distillation method that creates an eau de vie with a higher alcohol content. After distillation, Armagnac carries an alcohol content of 54% ABV (making it the spirit the closest in alcohol levels to wine), while Cognac carries 72% ABV. The evaporation of the alcohol during aging permits Armagnac to obtain the commercial alcohol content of 40% ABV-45% ABV.
Armagnac’s aging process gives it its singular complexity. It is this aspect of its character that allows it to be attached more to wine culture than other brandies. Like wine, Armagnac can be made into a vintage to reflect the expression of one particularly good year. Cognac, however, is progressively diluted with water in order to reach the same level of 40% ABV-45% ABV.
Armagnac and Cognac have two distinct historical trajectories that influence their modern popularity. Armagnac was developed under a French model of conservation while Cognac was established under an export model more along the lines of the Netherlands or England.