Terms

• While the terms "scallion" and "green onion" are often use interchangeably in the United States, there are subtle but specific differences between the two. Scallion is actually a broad term used to refer to various types of onions, including green onions, young leeks and scallions themselves. Green onion refers to a new onion harvested while its top is still green and the bulb is still small.
  
  

Maturity

• Scallions are younger and less developed than green onions. Scallions are harvested when their tops are still green but the onion bulbs have not yet began to form. Green onions are harvested once a small bulb begins to form.
  
  

Appearance

• Knowing that scallions are harvested earlier and are, therefore, less developed than green onions aids in identifying the two based on appearance. The less-developed scallions have green tops which lead straight down into a white base. Since the bulb has yet to begin to develop, the base is approximately the same diameter as the top. Once the base widens into a bulb of roughly 3/4 inch wide, it becomes a green onion.
  
  

Flavor

• As onions mature, their flavor becomes more potent. Because of this, scallions are more mild in flavor compared to green onions. The leaves of scallions can be eaten and are hollow, much like chives. Because of the mild flavor, both the green tops and the white bottoms of scallions can be eaten raw or cooked. By contrast, the leaves of green onions have an unpleasant taste that causes them to be considered inedible. The bulb of green onions is most often cooked before consumption.