white lily vs Madonna lily

white lily and Madonna lily both are nouns.

Word	Noun	Adjective	Verb	Adverb
white lily	Yes	No	No	No
Madonna lily	Yes	No	No	No

As nouns, white lily and Madonna lily are synonyms defined as:

white lily and Madonna lily: lily of eastern Mediterranean and the Balkans with broad funnel-shaped white flowers

Other synonyms of white lily include Annunciation lily, Lent lily, Lilium candidum.

white lily (noun)	Madonna lily (noun)
lily of eastern Mediterranean and the Balkans with broad funnel-shaped white flowers	lily of eastern Mediterranean and the Balkans with broad funnel-shaped white flowers
white Egyptian lotus: water lily of Egypt to southeastern Africa; held sacred by the Egyptians