butterfly orchid vs butterfly orchis

butterfly orchid and butterfly orchis both are nouns.

Word	Noun	Adjective	Verb	Adverb
butterfly orchid	Yes	No	No	No
butterfly orchis	Yes	No	No	No

As nouns, butterfly orchid and butterfly orchis are synonyms defined as:

butterfly orchid and butterfly orchis: Mediterranean orchid having usually purple flowers with a fan-shaped spotted or striped rose-red lip

Other synonyms of butterfly orchid include Orchis papilionaceae.

As nouns, butterfly orchid and butterfly orchis are synonyms defined as:

butterfly orchid and butterfly orchis: Mexican epiphytic orchid having pale green or yellow-green flowers with white purple-veined lip

Other synonyms of butterfly orchid include Encyclia venosa, Epidendrum venosum.

butterfly orchid (noun)	butterfly orchis (noun)
any orchid of the genus Psychopsis: spectacular large tiger-striped orchids	Mediterranean orchid having usually purple flowers with a fan-shaped spotted or striped rose-red lip
Mediterranean orchid having usually purple flowers with a fan-shaped spotted or striped rose-red lip	Mexican epiphytic orchid having pale green or yellow-green flowers with white purple-veined lip
orchid of Florida and the Bahamas having showy brightly colored flowers; sometimes placed in genus Epidendrum
Mexican epiphytic orchid having pale green or yellow-green flowers with white purple-veined lip
any orchid of the genus Oncidium: characterized by slender branching sprays of small yellow and brown flowers; often grown as houseplants