sansevieria vs agave

sansevieria and agave both are nouns.

Word	Noun	Adjective	Verb	Adverb
sansevieria	Yes	No	No	No
agave	Yes	No	No	No

As nouns, agave is a hypernym of sansevieria; that is, agave is a word with a broader meaning than sansevieria:

sansevieria: grown as a houseplant for its mottled fleshy sword-shaped leaves or as a source of fiber
agave: tropical American plants with basal rosettes of fibrous sword-shaped leaves and flowers in tall spikes; some cultivated for ornament or for fiber

Other hypernyms of sansevieria include American aloe, century plant.

sansevieria (noun)	agave (noun)
grown as a houseplant for its mottled fleshy sword-shaped leaves or as a source of fiber	tropical American plants with basal rosettes of fibrous sword-shaped leaves and flowers in tall spikes; some cultivated for ornament or for fiber