There are all kinds of onions, green, red, yellow, sweet, and downright spicy. How to tell the differences between spring onion versus green onion can be tricky, but we’re here to help you out. Both vegetables have long, with green stalks, and a white bottom that forms the bulb of the plant. The major differences come down to when they are harvested, which in turn affects the flavor, as well as the size of the bulb. These traits also affect when to use spring onion versus green onion in certain recipes. The easiest way to compare the two is that spring onions are a more mature version of green onions. Both are young onions that have not fully matured in terms of bulb size or flavor.