cuckoo flower vs catchfly

cuckoo flower and catchfly both are nouns.

Word	Noun	Adjective	Verb	Adverb
cuckoo flower	Yes	No	No	No
catchfly	Yes	No	No	No

As nouns, catchfly is a hypernym of cuckoo flower; that is, catchfly is a word with a broader meaning than cuckoo flower:

cuckoo flower: common perennial native to Europe and western Asia having usually pink flowers with ragged petals
catchfly: mostly perennial herbs with sticky stems that catch insects; widespread in north temperate zone

Other hypernyms of cuckoo flower include lychnis.

cuckoo flower (noun)	catchfly (noun)
common perennial native to Europe and western Asia having usually pink flowers with ragged petals	mostly perennial herbs with sticky stems that catch insects; widespread in north temperate zone
a bitter cress of Europe and America	any plant of the genus Silene