spike rush vs sedge

spike rush and sedge both are nouns.

Word	Noun	Adjective	Verb	Adverb
spike rush	Yes	No	No	No
sedge	Yes	No	No	No

As nouns, sedge is a hypernym of spike rush; that is, sedge is a word with a broader meaning than spike rush:

spike rush: a sedge of the genus Eleocharis
sedge: grasslike or rushlike plant growing in wet places having solid stems, narrow grasslike leaves and spikelets of inconspicuous flowers

spike rush (noun)	sedge (noun)
a sedge of the genus Eleocharis	grasslike or rushlike plant growing in wet places having solid stems, narrow grasslike leaves and spikelets of inconspicuous flowers