yellow water flag vs yellow flag

yellow water flag and yellow flag both are nouns.

Word	Noun	Adjective	Verb	Adverb
yellow water flag	Yes	No	No	No
yellow flag	Yes	No	No	No

As nouns, yellow water flag and yellow flag are synonyms defined as:

yellow water flag and yellow flag: common yellow-flowered iris of Europe and North Africa, naturalized in United States and often cultivated

Other synonyms of yellow water flag include Iris pseudacorus, yellow iris.

yellow water flag (noun)	yellow flag (noun)
common yellow-flowered iris of Europe and North Africa, naturalized in United States and often cultivated	common yellow-flowered iris of Europe and North Africa, naturalized in United States and often cultivated