Only brandy produced in the Armagnac region of France can carry the name Armagnac. Along with Cognac it is one the most well known types of brandy but the difference between Armagnac and Cognac is more than just region and name.
Unlike Cognac, which is double distilled in pot stills, the spirit for Armagnac is produced during a single distillation in a column still. The resulting spirit is often fuller but typically requires longer maturation time in casks.
Armagnac production is frequently carried out on a less industrial scale too, leading to a plethora of small batch bottlings. Age labeling is also often less ambiguous than Cognac, perhaps due to the need for the spirit to mature longer, and bottles are typically labeled with their vintage and year of bottling.
Due in part to the smaller scale artisanal production, and relatively uncommercial nature of the Armagnac business, some fine aged brandies can be found from this region at less exalted prices than many of their more famous cousins from the Cognac region.