
Brandy is a spirit distilled from wine or fermented fruit, usually aged in oak. Labeled just "brandy", it’s the grape kind; fruit brandies carry their own names — Calvados from apples, kirsch from cherries.
Aged grape spirit is a broad family and the bottles inside it are genuinely interchangeable; what differs is age, region and price. The label word tells you less than the age statement does.
Cognac, Armagnac and Spanish brandy
All of them are brandy — protected regional styles, not separate spirits — and any will carry a brandy recipe with its own accent. Cognac reads finer, Armagnac bolder, the Spanish sweeter from its sherry casks; only the last needs the syrup pulled back.
Grappa and marc
Distilled from pomace rather than wine, so they are a different branch entirely. In place of brandy they leave a stirred drink rustic and hard-edged, and no adjustment of measure softens that.
The range of styles shows on the French examples: cognac is twice-distilled in copper pots and comes out finer, Armagnac usually once and at lower strength, which leaves it bolder and more aromatic.

Sazerac
Rye whiskey, Bourbon, Brandy

Between The Sheets (David Wondrich recipe)
Brandy

Brandy Crusta
Brandy

Brandy Julep
Brandy

Angels Share No. 1
Brandy

Brandy Sangaree
Brandy

Fish House Punch
Brandy, Light gold rum

Suffering Bastard – IBA
Brandy, London dry gin, Ginger beer

Christmas Port Flip
Ruby port

Porto Flip – IBA
Tawny port