spring onion vs green onion

spring onion and green onion both are nouns.

Word	Noun	Adjective	Verb	Adverb
spring onion	Yes	No	No	No
green onion	Yes	No	No	No

As nouns, spring onion and green onion are synonyms defined as:

spring onion and green onion: a young onion before the bulb has enlarged; eaten in salads

Other synonyms of spring onion include scallion.

spring onion (noun)	green onion (noun)
a young onion before the bulb has enlarged; eaten in salads	a young onion before the bulb has enlarged; eaten in salads