Brandy is a broad overall category which includes all distilled products issued from fermented fruits. Hence, it includes sub-categories such as Armagnac, Calvados, Grapa, Pisco, Eau-de-Vie, ... but also 'Cognac'. Another sub-category is also brandy which is commonly known as an aged distilled grape wine. The problem with brandy as a sub-category is that often these brandies are the results of distillation of 'cheap' wines and therefore they produce less interesting distillates which are less regulated and protected and maybe manipulated in such a way to improve the original product. Such manipulations may enhance smoothness, taste and color by adding something to 'enhance'.
Some cultures and countries have a real tradition in making brandy of wines like Spain or Armenia. They both have a set of specific traditions in aging and producing but at the end they produce a much sweeter brandy than say French brandy.
French brandies (i.e. generic of wines) appear in a wide variety of quality levels with some being 'the run of the mill' and other being absolutely outstanding.
Germans have a strong reputation in making brandy covering a wide spectrum of quality products, but they are most generally famous for their quality eaux-de-vie. In Germany they do not call these brandies or eaux-de-vie but schnapps. The fruits most used for Schnapps are are apricot, apples, cherries, pears, and plums. In some situation, they use raspberries or rather they infused raspberries with rectified grape brandies because the raspberries produce a low yield of alcohol due to their low sugar content. In addition, a 100% raspberry brandy/schnapps will require too many fruits and would turn too expensive.
The concept behind eau-de-vie is to be a brandy which expresses the typicity of the fruits originally fermented. Hence, eaux-de-vie made of fermented apricots should taste and smell like concentrated apricots. Eaux-de-vie can but are therefore rarely aged for the sake of keeping the typicity of the fruits being used. Apple Jack are brandy made of fermented apples. In this situation, one would not want to age too much their apple jacks to keep the typicity of the apples.
Calvados is a geographic indication (issue related to trademark) and/or an 'appellation d'origine controllee' (issue related to French regulations) . In the case of Calvados, the apple expression is very much revealed in young Calvados whereas older Calvados become richer super-premium brandy like where the expression is to reveal complexity and facets, and where the apples characteristics fade away with time.
Consequently cognac is a brandy and more specifically a double distilled grape wine from Charentes, Deux Sevres and Vienne in compliance with the French regulated "appellation d'origine controlee".
