Thank you. ;o)
White onions have a stronger "onion flavor". Moving down the onion ladder, brown onions and then "sweet" onions such as Walla Walla, Maui, Vidalia get milder and in my opinion, taste much better.
Agree with pierino, but I honestly think they can be interchanged pretty easily UNLESS the onions are a really big component of the dish. I definitely prefer yellow for caramelizing since they are sweeter naturally.
Vidalia onions are much sweeter!
Chef Laura at Home
I agree with JessicaBakes, white and yellow varieties can be interchanged except when you are building a dish on caramelized onions, yellows are best for that. Raw white or red onions can be used in fresh salsas, most people find red onions best served raw. You can tone down the "onion" by putting slices in an ice bath.
Most storage onions, which can keep as long as 9 months or more, are yellow onions. Copra is a common variety. Most people would consider them to have a stronger flavor, although varies hugely depending on where they are grown. Many white onions are so-called sweet onions, like Walla Walla, Vidalia, Ailsa Gray, the so-called Spanish onion, and so on. Often (although not always, again depending on where and how they are grown)) they are less harsh-tasting when eaten raw. They generally don't keep for more than a few months in storage. And then there is the red onion..... As you can see by my use of terms like "generally," the onion you buy in the store is subject to a lot of influences pertaining to cultivation, variety, etc. so it is really hard to be definitive on this subject! Me? I use what I've got at the moment. Right now, I've used up the white onions since they won't store and have progressed to using up the red, since their storage quality is so-so. By January it'll be all yellows (stored cool, dark, and dry), some of which will still be good next June.
Also, white onions tend to have a higher water content. Within the yellow onion variety itself, the flatter the onion, the more sulfuric compounds it has and the more it makes you tear.
Thanks, everyone! I used the large white onion I had in my French Country Soup (recipe posted here, somewhere). I just sweat the onion at the outset in that recipe. Or at least that's all I did today. It turned out just fine. I didn't notice a bit of difference. Thanks again. ;o)