crab apple vs crab apple

crab apple and crab apple both are nouns.

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

crab apple (noun)	crab apple (noun)
small sour apple; suitable for preserving	small sour apple; suitable for preserving
any of numerous wild apple trees usually with small acidic fruit	any of numerous wild apple trees usually with small acidic fruit
any of numerous varieties of crab apples cultivated for their small acidic (usually bright red) fruit used for preserves or as ornamentals for their blossoms	any of numerous varieties of crab apples cultivated for their small acidic (usually bright red) fruit used for preserves or as ornamentals for their blossoms