calypter vs alula

calypter and alula both are nouns.

Word	Noun	Adjective	Verb	Adverb
calypter	Yes	No	No	No
alula	Yes	No	No	No

As nouns, calypter and alula are synonyms defined as:

calypter and alula: scalelike structure between the base of the wing and the halter of a two-winged fly

calypter (noun)	alula (noun)
scalelike structure between the base of the wing and the halter of a two-winged fly	tuft of small stiff feathers on the first digit of a bird's wing
	scalelike structure between the base of the wing and the halter of a two-winged fly