order Ephemeroptera vs order Ephemerida

order Ephemeroptera and order Ephemerida both are nouns.

Word	Noun	Adjective	Verb	Adverb
order Ephemeroptera	Yes	No	No	No
order Ephemerida	Yes	No	No	No

As nouns, order Ephemeroptera and order Ephemerida are synonyms defined as:

order Ephemeroptera and order Ephemerida: the order of mayflies or shadflies (Ephemeroptera, Ephemerida)

Other synonyms of order Ephemeroptera include Ephemerida, Ephemeroptera.

order Ephemeroptera (noun)	order Ephemerida (noun)
the order of mayflies or shadflies (Ephemeroptera, Ephemerida)	the order of mayflies or shadflies (Ephemeroptera, Ephemerida)