Cognac is essentially distilled alcohol from grapes… think about using wine to make distilled alcohol. I’m not positive, but I think I t was originally a way monks thought they could preserve wine through distillation and reconstitute it back into wine at a later time, but turns out not to have worked like that. Once you boil off the alcohol and discard the mash, you don’t get the ‘wine’ part back.

It’s just a different base to ferment and distill into a hard spirit. Because it starts as a sweeter fruit than grains, like rye, wheat, or barley, it tends to have a sweeter flavor. It’s particularly nice as a warm drink in the winter, but a bit sweeter than bourbon.