merl vs European blackbird

merl and European blackbird both are nouns.

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

As nouns, merl and European blackbird are synonyms defined as:

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

merl (noun)	European blackbird (noun)
common black European thrush	common black European thrush