Knowing the difference of the allium family, between shallots, green onions, scallions, chives and leeks can be very confusing. One reason is that the same common names are applied to more than one variety.
Aside from some marked differences in flavour, although they are related, they also look and grow differently.
Allium fistulosum, the young green onion, spring onion or the bunching onion as it is often called in the family, is a perennial, although it is grown as an annual here. The lower white part is fleshier than the chive and its long green narrow and hollow leaves can reach up to 50 centimetres. The spring onion has a slightly spicy taste, somewhere between the chive and the onion. There are two main types, the Japanese bunching onion and the Welsh bunching onion, which is the one mainly grown for consumption here, although there are some crosses with Allium cepa that have been developed in the U.S.
The shallot, Allium cepa var. aggregatum, can be distinguished from the others in the family by its distinctive bulbs, which are made up of cloves like garlic, but unlike garlic, the individual bulbs are not held together by a common membrane.
Allium schoenoprasum is native to both North America and Europe. You may grow the clumps ornamentally in the garden for their pretty purple flowers and round green stems. They are repulsive to most insects but attractive to bees. Harvest their tops by cutting right back to the ground. A fresh batch will soon replace your harvest. Flowers can be used in salads.