The simplest difference between the two is the color. The purple onion skin is purple, which is also common. But the white onion skin, is very white kind, the shape is the round ball, also some are the oblate ball.
The purple onion is very thin, showing a reddish color, not a lot of water, but it's very crisp, and it smells stronger. The white onion is very thick and contains more water than the purple one.
The purple onion is not very sweet, and the taste is spicy; while the white onion is not so spicy as the dessert. And the preservation method also has the difference, the white is not very good preservation.
In contrast, the output is very different. The output of purple is very high, and the output of white is very low.
