squill vs spring squill

squill and spring squill both are nouns.

Word	Noun	Adjective	Verb	Adverb
squill	Yes	No	No	No
spring squill	Yes	No	No	No

As nouns, spring squill is a hyponym of squill; that is, spring squill is a word with a more specific, narrower meaning than squill:

squill: an Old World plant of the genus Scilla having narrow basal leaves and pink or blue or white racemose flowers
spring squill: European scilla with small blue or purple flowers

Other hyponyms of squill include Scilla verna, sea onion.

squill (noun)	spring squill (noun)
an Old World plant of the genus Scilla having narrow basal leaves and pink or blue or white racemose flowers	European scilla with small blue or purple flowers
having dense spikes of small white flowers and yielding a bulb with medicinal properties
bulb of the sea squill, which is sliced, dried, and used as an expectorant