Much of the difference between bottles has to do with how long they are aged. Younger VS, or “very special,” cognac is blended from brandies at least two years old, while an XO cognac, or “extra-old” cognac, gets its rich depth because it must be aged at least six years. The VSOP, or “very superior old pale” cognacs, blended from four-year and older brandies, are right in the middle, with characteristics of both youth and age.