merl vs Turdus merula

merl and Turdus merula both are nouns.

Word	Noun	Adjective	Verb	Adverb
merl	Yes	No	No	No
Turdus merula	Yes	No	No	No

As nouns, merl and Turdus merula are synonyms defined as:

Other synonyms of merl include blackbird, European blackbird, merle, ousel, ouzel.

merl (noun)	Turdus merula (noun)
common black European thrush	common black European thrush