One of my pet peeves in language is the misuse of the words further and farther. The two have distinct and specific meanings and should be used appropriately.
Similarly, the words varietal and variety have two distinct meanings, but are often misused, and are thought to be interchangeable. Until recently, I was under the impression that these two words were interchangeable. I was wrong. And now, enlightened by a viticulturist, I am spoiled, forever to cringe and grind my teeth when I hear people with a long history of working in the wine industry and a substantial knowledge of wine talk about a grape varietal.
For clarification, with help from Wikipedia:
Variety refers the kind of fruit, the specific cultivar within that species (vitis vinifera).
Varietal describes wines made from a grape variety, and which typically displays the name of that variety on the wine label.
Thus, varietal is an adjective; Of, indicating, or characterizing a variety. Variety is a noun; A group that is distinguished from other groups by a specific characteristic or set of characteristics.