bulbous iris vs fleur-de-lis

bulbous iris and fleur-de-lis both are nouns.

Word	Noun	Adjective	Verb	Adverb
bulbous iris	Yes	No	No	No
fleur-de-lis	Yes	No	No	No

As nouns, fleur-de-lis is a hypernym of bulbous iris; that is, fleur-de-lis is a word with a broader meaning than bulbous iris:

bulbous iris: any of various irises having a rootstock formed like a bulb
fleur-de-lis: plants with sword-shaped leaves and erect stalks bearing bright-colored flowers composed of three petals and three drooping sepals

Other hypernyms of bulbous iris include flag, iris, sword lily.

bulbous iris (noun)	fleur-de-lis (noun)
any of various irises having a rootstock formed like a bulb	(heraldry) charge consisting of a conventionalized representation of an iris
	plants with sword-shaped leaves and erect stalks bearing bright-colored flowers composed of three petals and three drooping sepals