Also known as scallions in America, spring onion is a type of root vegetable. They have a white fleshy root bulb with light green leaves. The tiny white fleshy bulb has a long slender green top, which is also edible. Spring onions have a slightly milder taste than the regular onions which are delight to the taste buds.
Welsh onion is a variety of spring onion that doesn't form into a bulb even after maturing. It is popularly used as a salad onion in the West.