Green Onions are a different name for the Scallion, Spring Onion, Salad Onion, Table Onion, Shallot, Green Shallot, Onion Stick, Long Onion, Baby Onion, Precious Onion, Yard Onion, Gibbon or Syboe. This is much dependent on what part of world you are from.
The green onion has green leaves that are hollow however it does not have a root bulb which is developed. This is quite unlike a normal common onion.
They are often eaten as part of a salad.
In particular their sugar, fat, phosphorous, acidic, protein and calcium content is particularly of interest.