The Difference Between Yellow and White Onions Is More Than Skin Deep

[Nittersing]

https://www.seriouseats.com/yellow-onion-vs-white-onion-8666582

White onions have a sharper, more distinct onion flavor than yellow onions. They tend to have a cleaner, crisper, and firmer texture, with a slightly brighter taste when raw and little to no aftertaste. When cooked, white onions break down more easily than their yellow counterparts—almost melting into long-cooked dishes like soups and stews.

Yellow onions have a more complex flavor profile, with a balance of sweetness and pungency. They have a more tender and slightly denser texture when raw, and the kind of aftertaste that can wake up the dead. When cooked, they soften further and become sweeter and more caramelized, but retain their structural integrity.

Sweet onions, sold under trademarked names such as Vidalia, Maui, and Walla Walla, are a type of yellow onion that is milder and seasonal. You’ll see them at the store during the spring and summer months. The more generically labeled yellow, white, and red onions available year-round are called storage onions because they’ve been dried out after harvest to keep for months. If you find these varieties at farmers markets, you may see them with specific tags like Red Zeppelins or Australian Browns.

Edit to add: Serious Eats also has a "Beginners Guide" to onions which goes into a lot of detail and includes spring onions, ramps, shallots, pearl onions, Cippolini Onions and leeks! https://www.seriouseats.com/differences-between-onions