Grocery stores label long, skinny, green-topped onions that have white bottoms as either scallions or green onions. But they are almost always the exact same plant, says Kat Barlow, a customer service technician for Territorial Seed Company in Oregon. Chives, on the other hand, are “typically considered an herb since the plant stays pretty tiny yet has a strong, pungent flavor that is good as a seasoning in smaller quantities.”
Specifically, green onions/scallions are the genus and species Allium fistulosum, a.k.a. the Japanese bunching onion or Welsh onion, says Dale W. McNeal, a professor emeritus of biology at the University of the Pacific in Northern California. According to Barlow, this species “stays small and does not form big bulbs”; she adds that the regular cooking onion (Allium cepa) may also occasionally be sold as a green onion or spring onion if it’s harvested early, before the bulb fully forms. The immature cepa has a stronger flavor than the fistulosum. Used raw, green onions/scallions add a bit of texture, color, and a milder taste to your cooking than regular onions, as in this recipe for guacamole. They are also delicious grilled whole.
“Chives are a completely different species, Allium schoenoprasum,” says McNeal. Use chives to add oniony flavor (with a tiny hint of garlic) without having to put big chunks in your dish, like in these soft-scrambled-egg and prosciutto bundles. Chives are also good raw as a garnish over things like deviled eggs. The genus Allium includes garlic, shallots, and leeks as well—the latter of which might also be confused with scallions when they are picked very young. The Latin name for the leek is Allium ampeloprasum var. porrum. Leeks are firmer and more dense than scallions, with a milder flavor. Recipes usually call for the light green and white portion of the stalk (but we like to save the green tops and throw them in the pot when making stock). Leeks are best in cooked preparations, like CHOW’s Savory Onion and Leek Tart or Carrot, Leek, and Parsley Mash.