First, they come from different places. Generally speaking, yellow onions are produced by ourselves in Chinese mainland. For red onions, it is more from the northwest. But for our developed traffic, no matter what kind of onions or other vegetables you like, you can easily buy them.
Secondly, they have different tastes. As we all know, onions have a pungent smell, which makes people cry easily. Compared with red onion, yellow onion tastes a little more spicy, so red onion is more suitable for some people with heavy taste. Yellow onions, on the other hand, are not so spicy and have a little sweetness. Therefore, yellow onion is more suitable for people with light taste.
Third, they cook in different ways. When we stew in a big pot, we can add red onion as seasoning to improve the taste of the dishes. As for the yellow onion, because it tastes mild, it can be eaten directly in cold salad, and we usually choose yellow onion when making curry, which is also delicious.
Fourth, they are also preserved in different ways. Yellow onions are bigger than red onions, so they contain a lot of water and are difficult to preserve. On the other hand, red onions will last longer because of their small size and low water content.
However, the nutritional value of the two is almost the same, which is only determined by personal hobbies.
The above is my personal view on this problem, I hope I can help you, thank you.