bird vs fille

bird and fille both are nouns.

As nouns, fille is a hypernym of bird; that is, fille is a word with a broader meaning than bird:

Other hypernyms of bird include miss, missy, girl, young lady, young woman.

bird (noun)	fille (noun)
warm-blooded egg-laying vertebrates characterized by feathers and forelimbs modified as wings	a young female
the flesh of a bird or fowl (wild or domestic) used as food
informal terms for a (young) woman
a cry or noise made to express displeasure or contempt
badminton equipment consisting of a ball of cork or rubber with a crown of feathers

bird (verb)	fille (verb)
watch and study birds in their natural habitat