What's the difference between a wine's balance and its structure?

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Dear Dr. Vinny,
If a wine’s structure is the relationship between its elements (acidity, tannins, glycerol and alcohol), then what is the difference between balance and good structure, or is it the same thing?
—Linda F., Sparks, Nev.
Dear Linda,
Balance and structure definitely overlap as wine terms, but I think you can still make a distinction: the term “balance” generally includes a wine’s aromas and flavors, but the term “structure” generally doesn’t. (Of course, not everyone uses these terms exactly the same way.)
As I said earlier, a wine’s overall structure is determined by how its structural elements come into play and relate to one another. But the word “balance” typically also evokes a wine’s flavors, and sometimes even its aromatics. So if a wine’s structure, flavors and aromas are all harmonious and in proportion, the wine would be considered balanced.
Balance can also be considered a matter of timing as you enjoy the wine. Do the wine’s aromatics smoothly give way to the flavors, which evolve into the finish? Does the structure help the wine express these notes? Or does jarring acidity, austere tannins or untoward sweetness get in the way? Sometimes it’s easier to describe a wine that’s not balanced—if a flavor, an element or some other aspect of the mouthfeel sticks out from the other components, the wine is unbalanced.
—Dr. Vinny