Answer:
Wines, like scotch and bourbon whiskey, can be made either from one or more varieties of grapes or grains. Most wines are blended from many species of grapes, both for reasons of taste (to get the best out of flavor, tannins, acidity, color and aroma) as well as for economic reasons. Varietal wines are usually more expensive being made from one grape variety, and also have more distinguishing characteristics of that particular grape without "muddying" the waters with a "kitchen sink" approach. A little bit like single malt scotch versus blended scotch or bourbon.