lemon lily vs daylily

lemon lily and daylily both are nouns.

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

As nouns, daylily is a hypernym of lemon lily; that is, daylily is a word with a broader meaning than lemon lily:

lemon lily: a day lily with yellow flowers
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

Other hypernyms of lemon lily include day lily.

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