delphinium vs larkspur

delphinium and larkspur both are nouns.

Word	Noun	Adjective	Verb	Adverb
delphinium	Yes	No	No	No
larkspur	Yes	No	No	No

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

delphinium: any plant of the genus Delphinium having palmately divided leaves and showy spikes of variously colored spurred flowers; some contain extremely poisonous substances
larkspur: any of numerous cultivated plants of the genus Delphinium

delphinium (noun)	larkspur (noun)
any plant of the genus Delphinium having palmately divided leaves and showy spikes of variously colored spurred flowers; some contain extremely poisonous substances	any of numerous cultivated plants of the genus Delphinium