alula vs spurious wing

alula and spurious wing both are nouns.

Word	Noun	Adjective	Verb	Adverb
alula	Yes	No	No	No
spurious wing	Yes	No	No	No

As nouns, alula and spurious wing are synonyms defined as:

alula and spurious wing: tuft of small stiff feathers on the first digit of a bird's wing

Other synonyms of alula include bastard wing.

alula (noun)	spurious wing (noun)
tuft of small stiff feathers on the first digit of a bird's wing	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