budgerigar vs Melopsittacus undulatus

budgerigar and Melopsittacus undulatus both are nouns.

Word	Noun	Adjective	Verb	Adverb
budgerigar	Yes	No	No	No
Melopsittacus undulatus	Yes	No	No	No

As nouns, budgerigar and Melopsittacus undulatus are synonyms defined as:

budgerigar and Melopsittacus undulatus: small Australian parakeet usually light green with black and yellow markings in the wild but bred in many colors

Other synonyms of budgerigar include budgereegah, budgerygah, budgie, grass parakeet, lovebird, shell parakeet.

budgerigar (noun)	Melopsittacus undulatus (noun)
small Australian parakeet usually light green with black and yellow markings in the wild but bred in many colors	small Australian parakeet usually light green with black and yellow markings in the wild but bred in many colors