Armagnac and Cognac are French eaux de vie under the AOC designation, which means that they cannot be produced outside of the region which bears their name.  300 km separates the two territories. Cognac is the northernmost of the two, including the Charente, Charente-Maritime and a little part of the Dordogne and the Deux-Sèvres departments. The terroirs are distinguished by their soil composition and their climate, giving each eau de vie its own specific characteristics. The Cognac soil is made up of a majority of limestone, whereas the soil of the Armagnac region is sandy, with clay-silica and clay-limestone properties.  The Armagnac region also has a dryer, sunnier Continental climate with harsher winters than its Cognac counterpart, which is considered to have an Oceanic climate.

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.