What’s the difference between a wine aerator and a wine preserver?

Hello there! I'm Dr. Vinifera, but you can call me Vinny. Ask me your toughest wine questions, from the fine points of etiquette to the science of winemaking. And don't worry, I'm no wine snob—you can also ask me those "dumb questions" you're too embarrased to ask your wine geek friends! I hope you find my answers educational, empowering and even amusing. And don't forget to check out my most asked questions and my full archives for all my Q&A classics.
Dear Dr. Vinny,
What’s the difference between a wine aerator and a wine preserver?
—Eden, California
Dear Eden,
Wine aeration and preservation actually serve opposing goals, but they both have to do with oxygen. An aerator is designed to introduce air into a wine to make it more expressive, accelerating the process served by swirling wine or pouring it into a decanter. Wine preservers are intended to extend the life of an open bottle of wine by limiting the wine’s exposure to oxygen. Check out our short videos on decanting and saving leftover wine for more on those two topics. To say wine has a complicated relationship with oxygen is an understatement.
When we first open a bottle of wine, air is great. Oxygen helps a wine “open up” or “breathe,” which allows it to become more expressive. Swirling wine in your glass, decanting it, or using an aerator all serve this purpose. Wine is composed of hundreds of compounds, and introducing oxygen will usually make the volatile, undesirable compounds evaporate faster than the desirable, aromatic and flavorful ones.
But anyone who has tasted a bottle of wine that’s been open for a few days can attest that too much exposure to air will flatten out the flavors and aromas, and eventually give wines the same oxidized notes as an apple that’s turned brown. Younger, more robust wines can take more oxygen before they start to fade than older, more fragile examples.
I don’t personally own an aerator or a wine preserver. I enjoy watching a wine evolve naturally in my glass, and I see no need to rush the process. I do have a decanter, which I employ whenever I suspect a wine will be particularly tight, or needs to be removed from its sediment.
As far as leftover wine (pausing for my readers who like to joke that they don’t know what “leftover wine” is), I store all of my leftover wine (red, white, rosé, sparkling, etc.) in the fridge, which slows down its deterioration. I also have a couple of empty half-bottles with screwcaps that I transfer the leftover wine into—the smaller container means there’s less oxygen inside the bottle to interact with the wine.
—Dr. Vinny