daylily vs lemon lily

daylily and lemon lily both are nouns.

Word	Noun	Adjective	Verb	Adverb
daylily	Yes	No	No	No
lemon lily	Yes	No	No	No

As nouns, lemon lily is a hyponym of daylily; that is, lemon lily is a word with a more specific, narrower meaning than daylily:

daylily: any of numerous perennials having tuberous roots and long narrow bladelike leaves and usually yellow lily-like flowers that bloom for only a day
lemon lily: a day lily with yellow flowers

Other hyponyms of daylily include Hemerocallis flava, Hemerocallis lilio-asphodelus.

daylily (noun)	lemon lily (noun)
any of numerous perennials having tuberous roots and long narrow bladelike leaves and usually yellow lily-like flowers that bloom for only a day	a day lily with yellow flowers