system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why are the glasses shaped differently for red and white wines?
gpt
Red wines tend to have stronger flavor compounds and tannins that soften when they "breathe" or decant.  The wider bowl of a red wine glass is believed to allow for more contact with the air, which means these soften a bit more and allow a greater distance from your nose to the wine so that the aromas aren't so intense.  The widest red wine glasses are Bordeaux glasses, because a lot of Bordeaux are high-alcohol and high-tannin, so the very wide shape allows both of those to mellow out much more.

White wines, on the other hand, tend to be a bit softer with less intense flavors - the smaller size is because they don't usually need to breathe, and they let your nose get that little bit closer to pick up the subtle aromas.  Many white wine glasses also have slightly longer stems, because white wine is often served chilled, and that keeps your hand away from the bowl so that you're not warming up the wine with the heat of your hand.

At the end of the day though, these are minor things and they're all generalities.  I've had people insist on serving specific white wines in wider red wine glasses because they were higher-alcohol than is common, for example.  And there have been studies that show that for most people, the difference is negligible between glasses, and even for experts there are disagreements about the "best" glass for a particular need.