cuckoo flower vs Lychnis flos-cuculi

cuckoo flower and Lychnis flos-cuculi both are nouns.

Word	Noun	Adjective	Verb	Adverb
cuckoo flower	Yes	No	No	No
Lychnis flos-cuculi	Yes	No	No	No

As nouns, cuckoo flower and Lychnis flos-cuculi are synonyms defined as:

cuckoo flower and Lychnis flos-cuculi: common perennial native to Europe and western Asia having usually pink flowers with ragged petals

Other synonyms of cuckoo flower include Lychins floscuculi, ragged robin.

cuckoo flower (noun)	Lychnis flos-cuculi (noun)
common perennial native to Europe and western Asia having usually pink flowers with ragged petals	common perennial native to Europe and western Asia having usually pink flowers with ragged petals
a bitter cress of Europe and America