snow-in-summer vs chickweed

snow-in-summer and chickweed both are nouns.

Word	Noun	Adjective	Verb	Adverb
snow-in-summer	Yes	No	No	No
chickweed	Yes	No	No	No

As nouns, chickweed is a hypernym of snow-in-summer; that is, chickweed is a word with a broader meaning than snow-in-summer:

snow-in-summer: chickweed with hairy silver-grey leaves and rather large white flowers
chickweed: any of various plants related to the common chickweed

Other hypernyms of snow-in-summer include clammy chickweed, mouse-ear chickweed, mouse ear, mouse eared chickweed.

snow-in-summer (noun)	chickweed (noun)
chickweed with hairy silver-grey leaves and rather large white flowers	any of various plants of the genus Stellaria
annual spurge of western United States having showy white-bracted flower clusters and very poisonous milk	any of various plants related to the common chickweed