alder fly vs Sialis lutaria

alder fly and Sialis lutaria both are nouns.

Word	Noun	Adjective	Verb	Adverb
alder fly	Yes	No	No	No
Sialis lutaria	Yes	No	No	No

As nouns, alder fly and Sialis lutaria are synonyms defined as:

alder fly and Sialis lutaria: dark-colored insect having predaceous aquatic larvae

Other synonyms of alder fly include alderfly.

alder fly (noun)	Sialis lutaria (noun)
dark-colored insect having predaceous aquatic larvae	dark-colored insect having predaceous aquatic larvae