Old World crayfish vs ecrevisse

Old World crayfish and ecrevisse both are nouns.

Word	Noun	Adjective	Verb	Adverb
Old World crayfish	Yes	No	No	No
ecrevisse	Yes	No	No	No

As nouns, Old World crayfish and ecrevisse are synonyms defined as:

Old World crayfish and ecrevisse: small crayfish of Europe and Asia and western North America

Old World crayfish (noun)	ecrevisse (noun)
small crayfish of Europe and Asia and western North America	small crayfish of Europe and Asia and western North America
	tiny lobster-like crustaceans usually boiled briefly