budgerigar vs parakeet

budgerigar and parakeet both are nouns.

Word	Noun	Adjective	Verb	Adverb
budgerigar	Yes	No	No	No
parakeet	Yes	No	No	No

As nouns, parakeet is a hypernym of budgerigar; that is, parakeet is a word with a broader meaning than budgerigar:

budgerigar: small Australian parakeet usually light green with black and yellow markings in the wild but bred in many colors
parakeet: any of numerous small slender long-tailed parrots

Other hypernyms of budgerigar include paraquet, paroquet, parrakeet, parroket, parroquet.

budgerigar (noun)	parakeet (noun)
small Australian parakeet usually light green with black and yellow markings in the wild but bred in many colors	any of numerous small slender long-tailed parrots