greylag vs Anser anser

greylag and Anser anser both are nouns.

Word	Noun	Adjective	Verb	Adverb
greylag	Yes	No	No	No
Anser anser	Yes	No	No	No

As nouns, greylag and Anser anser are synonyms defined as:

greylag and Anser anser: common grey wild goose of Europe; ancestor of many domestic breeds

Other synonyms of greylag include graylag, graylag goose, greylag goose.

greylag (noun)	Anser anser (noun)
common grey wild goose of Europe; ancestor of many domestic breeds	common grey wild goose of Europe; ancestor of many domestic breeds