western crab apple vs Iowa crab

western crab apple and Iowa crab both are nouns.

Word	Noun	Adjective	Verb	Adverb
western crab apple	Yes	No	No	No
Iowa crab	Yes	No	No	No

As nouns, western crab apple and Iowa crab are synonyms defined as:

western crab apple and Iowa crab: wild crab apple of western United States with fragrant pink flowers

Other synonyms of western crab apple include Iowa crab apple, Malus ioensis, prairie crab.

western crab apple (noun)	Iowa crab (noun)
wild crab apple of western United States with fragrant pink flowers	wild crab apple of western United States with fragrant pink flowers