blackbird vs merl

blackbird and merl both are nouns.

Word	Noun	Adjective	Verb	Adverb
blackbird	Yes	No	No	No
merl	Yes	No	No	No

As nouns, blackbird and merl are synonyms defined as:

Other synonyms of blackbird include European blackbird, merle, ousel, ouzel, Turdus merula.

blackbird (noun)	merl (noun)
any bird of the family Icteridae whose male is black or predominantly black	common black European thrush
common black European thrush