Danaus plexippus vs danaid

Danaus plexippus and danaid both are nouns.

Word	Noun	Adjective	Verb	Adverb
Danaus plexippus	Yes	No	No	No
danaid	Yes	No	No	No

As nouns, danaid is a hypernym of Danaus plexippus; that is, danaid is a word with a broader meaning than Danaus plexippus:

Danaus plexippus: large migratory American butterfly having deep orange wings with black and white markings; the larvae feed on milkweed
danaid: large tropical butterfly with degenerate forelegs and an unpleasant taste

Other hypernyms of Danaus plexippus include danaid butterfly.

Danaus plexippus (noun)	danaid (noun)
large migratory American butterfly having deep orange wings with black and white markings; the larvae feed on milkweed	large tropical butterfly with degenerate forelegs and an unpleasant taste