dwarf iris vs vernal iris

dwarf iris and vernal iris both are nouns.

Word	Noun	Adjective	Verb	Adverb
dwarf iris	Yes	No	No	No
vernal iris	Yes	No	No	No

As nouns, dwarf iris and vernal iris are synonyms defined as:

dwarf iris and vernal iris: low-growing spring-flowering American iris with bright blue-lilac flowers

Other synonyms of dwarf iris include Iris verna.

dwarf iris (noun)	vernal iris (noun)
low-growing spring-flowering American iris with bright blue-lilac flowers	low-growing spring-flowering American iris with bright blue-lilac flowers
low-growing summer-flowering iris of northeastern United States