snow trillium vs trillium

snow trillium and trillium both are nouns.

Word	Noun	Adjective	Verb	Adverb
snow trillium	Yes	No	No	No
trillium	Yes	No	No	No

As nouns, trillium is a hypernym of snow trillium; that is, trillium is a word with a broader meaning than snow trillium:

snow trillium: a low perennial white-flowered trillium found in the southeastern United States
trillium: any liliaceous plant of the genus Trillium having a whorl of three leaves at the top of the stem with a single three-petaled flower

Other hypernyms of snow trillium include wake-robin, wood lily.

snow trillium (noun)	trillium (noun)
a low perennial white-flowered trillium found in the southeastern United States	any liliaceous plant of the genus Trillium having a whorl of three leaves at the top of the stem with a single three-petaled flower